Funding lawsuits for profit is a well-known society anti-pattern called "champerty." It is no longer illegal (as blocking it interfered with access to justice) but when used for profit or other agendas it is pretty damaging (think patent trolls).
Champerty (the funding of the litigation of others) is a problem in no small part because it allows the wealthy to engage in barratry (frivolous or vexatious litigation).
By "other agendas" I meant any issue not claimed in the lawsuit at hand, not agendas that differed from my own. It is a bit of a subjective point as one could have a legitimate interest in funding somebody who has been harmed in the same way you have in a different event (so you would not have standing, but at least a related agenda). But funding a suit you have no real interest in just "for the win" is a bit wild.