This is happening in 0.5 security space and above:
An individual sits within range of a station, and targets capsules and shuttles as they exit the station, using a Thrasher. Since this individual knows they are going to get killed by Concord, they simply refit another ship within a few minutes and rinse/repeat, and apparently make enough from the loot (this is at a major trade station) that they do not care about losing their ship.
This individual is in a player-owned corporation with only two members, so I will presume it’s one-man corp. Since this individual has been doing this repeatedly, the cost of losing their ship is bearable to them…so as long as they are sitting near the trade station doing this, what recourse is there that will hurt them? Since they are getting killed by Concord repeatedly, if I attack them it will just be another inconsequential ship lose to them.
If you think they are doing if for profit, then you could focus on stealing the loot before they scoop it.
Also, if they do this long enough they will gain low sec status and be free-to-shoot, as well as acquire public kill rights you can use to use shoot them. I agree that once they have committed a criminal act, you are wasting your time trying to get in on the CONCORD kill, but if you explode them before they can get a kill enough times, that will cost them time and resources, and might drive them off.
Just be wary, if they are near a station (or have an Orca or other ship that can carry other ships nearby) they may be trying to bait you into attacking them. They would then hop out of the Thrasher and into a much more capable combat ship to continue the fight you started with them.
As Black Pedro said, they may be doing it for the loot.
They may also be doing it just for fun.
Or they may be New Order agents shooting anyone without a permit.
Apart from shooting them directly / wardeccing them / bumping them, have you thought of talking to them and asking them about their motivation? Or maybe negotiating a deal of not shooting you?
Your best course of action, if you do not want counter-play, is avoidance. Create two bookmarks for the station in question, one for an instawarp from undock the other at zero to the station so you can immediately dock. If done properly it will be very difficult for them to do this to you.
If you want counter-play… like @Black_Pedro said… steal their loot, just be aware this makes you “the bad guy” as well and opens you up to all sorts of reprisals, just as they were.
If they have bounty, no harm in getting in on the concord km, just make sure they are all flashy red, if you are the only player on it you will get the bounty… but that doesn’t do anything really aside from padding your wallet… maybe.
As noted above, you need to create insta-warp and insta-dock bookmarks for getting into and out of each trade hub. I rarely go in and out a trade hub without using them.
I don’t see any Killboard info on you; can you link the kill?
This stuff confused me when I 1st started playing but you will adapt and learn to avoid these things after awhile.