If you want to set a business up and live in France forreals, then don't do that, and read below.
tl;dr - france is not a culture celebrated for its high risk profile. it celebrates its past and culture, things it wishes to preserve. everything else suffers because of this.
Moving from US to France all of your costs are going to go up. It's really hard to get French people to adopt the latest trends. Historically things are very conservative with the benefit of the doubt erring on the side of the status quo.
Any legal, gov't, or bureaucratic issues you think you have in the US, you can multiply by 20 if you set up in france.
The whole taxation system in France was never designed to deal with risk-heavy entreprises. If you employ someone, you must budget for paid vacation. To employ them at all, you need to draft either a CDI (Contract Duration Indeterminée)which means basically that you're employing them for life, or CDD (Contract Duration Determiné) which means you employ them on short term contract only. So either you marry them or you can't promise them much upside.