Scale. The amount that the capitalists steal from you is orders of magnitude larger than whatever infinitesimal amount of tax dollars (well, more accurately, cents) you lose because an unhoused person used a loophole to buy drugs. Personally I can't even imagine being angry at the two people you mentioned. Nor is there a realistic way to prevent those things that wouldn't punish the 99% of people who just use EBT to buy food like its intended.

(I also really don't care if people find a way to use EBT money to buy something else in general. Like I can't think of a single reason to be bothered by that. And I life off EBT and only ever use it the "correct" way.)