Been there, but found having a good group to fly with, a group you can spitball with on any topic (realworld or game), a group that will laugh with you, and at you when you do something stupid, and can take it just as good as they give it.
Its hard to find, but when you do it makes it worthwhile jumping on discord and in game, just to throw thoughts around.
quit the game.
Enjoy life.
Most people are completely missing the issue here.
You have everything.
THAT is where your struggle comes from.
When you didn’t have “everything and enough isk”, you had no struggle.
Your “goal” was to accumulate wealth. That’s what lower instincts dictate.
Contrary to popular belief, hoarding stuff and money isn’t really a good goal.
When your “Life” revolves around gathering stuff and isk,
then you didn’t have much of a “Life”,
which is proven now that you’ve achieved your goal.
You’re through with everything potentially gatherable
and you have more ISK than you know what to do with.
Yet … you’re feeling empty. Aimless.
When you realize that “Life” doesn’t revolve around hoarding and gathering,
because it actually doesn’t fill the emptyness that now surfaced,
then you have room to evolve beyond that.
You shouldn’t be asking “what to do in the game now”,
but instead should ask yourself “Is this really how I want to spend my time?”
If the answer is “Yes”, then - as this thread proves - your “Life” is quite empty.
If the answer is “No”, then I suggest you stop thinking about what to do
and instead ask yourself “What can I do to get rid of all this worthless crap in fun ways?”.
As you now probably understand … your crap has zero value,
because it doesn’t actually make “Life” fulfilling, otherwise you’d not be in this situation.
Wise stuff here…but you can’t have my things.
Good, because I really don’t want any of that. 
It’ll just get converted into something more meaningful:
Explosions!
To be honest with you, I fell into that exact trap you outlined.
Still sitting on the fence as to what to do though…
(sad face)
I bought an Orca and exploded it.
That was fun.
But Null is quite empty so it took a bit.
Explosions are down this season, unless you count destroyers.
You know, speaking of which, how do you even hire crew for a destroyer?
The Drifters bring hard and challenging content if you are into pve.
If you have too much isk, too many characters and accounts it all becomes meaningless. Here are some ideas that have worked for me in the past (or now).
stop using several accounts, slink back to just 1. That makes it more personal, it makes it less meaningless.
make a fresh alt/account, do not “help” it and try a completely different play style
find a play style that requires or forces you to interact with others more, in a different way than you’re used to.
One of the best way to get rid of the emptyness is embracing it,
diving into it and feeling it until it turns into something else.
Sheesh, that sounds like it’s from some sort of therapy but what do I know!
Resisting it yields nothing useful.
Distraction yields nothing useful.
The end result is a state of lethargy.
Apathy. Which one was it again?
Man, I have no clue. Zero. Sad Panda. 
So I guess that only leaves us with working with it! If I knew what I was talking about, I’d tell you about how it’s really helpful just diving into it, feeling it out, etc. etc, but I know nothing of sorts about this stuff.
Hell, I’d probably recommend working the opposite of what you want to do.
*skips the lesson about Needs and Wants and the differences*
Hey, how about this!
You can work with something in many ways!
You wanted to amass ships and wealth!
Do the opposite, especially if you don’t want to do it …
… then see what happens in you.
A simple way of overcoming this silly mindset of being required to want something is by simply doing something and disregarding if it actually wanted. This is true for everything in Life. Most people do not question their Wants and they don’t understand them, they just assume they’re coming from themselves and their own will, without having any actual rational concept of it.
The best advice I can give you is to stop waiting for some factor to cause a Want and instead be the factor yourself by applying Willpower and just doing something. In your case it’s actually really easy, because your guide can be:
Do what you don’t want to do and learn how it makes a difference in your “Life”.
(don’t do ■■■■ that harms you or anyone else in real life. Apply common sense, or I’ll be forced to slap some into you)
My RL is pretty great BTW…it’s in game that I’m having the exact issue you are mentioning…
Great advice though…I’ll let you know what I decide…(soon!)
Solo combat.
Solo PvP in silly ships. Crash gate camps solo. Feels great. Try abyssal PvP. Small gang is my fave PvP. Need to do some myself to be honest.
Malango we should group and do some pvp lol
It was worse than that, it was City of Heroes.
Many great suggestions already given. My own small thoughts:
Actually do take a few months break and see what you actually start to miss;
You can keep multiple Toons/accounts, but only fly one toon at a time with full attention. This really changed a lot for the better for me;
Only point which I maybe missed here in the replies is: Next level of political / power career. When you are really this old/experienced in EvE, maybe really a next step should be ruling / influencing power. Either through working up in an existing alliance, or starting your own. Together with actually starting multimedia / websites / streaming content and the like for becoming more of a public influencer. (If you aren’t ofcourse already bussy along these lines)
You are talking about my retirement plan 
… cross fingers EvE will survive the next couple decades.
I’m not sure it’s possible to give a meaningful answer without understanding what do you mean by “everything is a struggle”.
Do you actually feel like you’d like to fly some ship and just don’t know what to do with it that you haven’t done already? Or is it more like you’re sitting in front of your computer screen simply because that’s what you’ve been doing all this time but now feels like it’s not calling anymore?
It could be that you simply need to take a break and get out more, do some physical exercise, etc…
Be a CCP developer.
I’m in the same boat…
Talk ■■■■ to everyone in Jita local and be as toxic as possible to everyone, especially corp mates. That’s what I do.