I - and since regretting it - rewatched the early MCU movies recently. The first time you really see Thanos mirrors the first frame, and the line immediately before he turns and smiles talks about how to invade Earth is "to court death." Given the comic book version, I'm not sure they had the whole 50% motivation thought through yet.
I'm not sure they've thought it through yet, although I do like the argument elsewhere in the thread that Thanos did it to prove he was right, not to save the universe.
My understanding is that the most basic of funerals and associated trappings is in excess of $10k (and that was prior to the current inflationary economic situation). Final healthcare expenses are likely also a few thousand dollars - and yes, the family likely has to pay it. So the amount of unexpected expenses is probably $25k to begin with... It starts seeming less excessive, to me at least.