It's funny, "hustler" definitely has a couple of meanings in American pop culture that would have negative connotations for most people. To a lot of people, it means something sorta like "con man" or "pool shark" and the connotation involves conning people out of their money. To other people it's synonymous with "drug dealer" which has it's own connotations.

BUT... "hustle" also has a pretty positive association in other contexts. For example, being a fan of (American)football, you often hear players described as "having hustle" which basically means "good work ethic, doesn't loaf on plays, always gives full effort until the whistle, etc."

And now we're seeing this startup related use of the word hustler which, to me, basically means "entrepreneur with hustle" or "entrepreneur who has great work ethic, works his butt off to find a way to achieve his goals, has pigheaded determination, etc." This almost strikes me as combining a bit of the connotations of the "drug dealer" thing with the football player example. Not exactly, but you can see elements of both... Anyway, used in this context, I don't see the problem with "hustler."