The merchant is still liable for chargebacks/fraud. So between future revenue, plus legal action if needed, Stripe can recover the money one way or another.

There's plenty of cashflow to negate the occasional fraud/chargeback. This is presumably how Venmo works.

It takes a very low % of chargebacks to completely negate any profits.

Profits for whom?

iirc, Stripe holds the platform liable, so they get paid either way.

So, the question is whether the extra fee they are charging is worth it, since you would be liable for chargebacks anyway?