I think the biggest difference though is that launching a B2B business is much harder to start with than a B2C one.

If you're a B2C one, you launch an app/website, you get small but basically instant feedback by signups/usage. Reward is potentially low per user however.

With B2B, even if you get in conversation with customers quickly, you still might be talking about a 6-12 months cycle to even get them signed up to a free trial. For large companies they want SSO, RBAC, etc. out of the door, plus RFC on security questionaires, data governance, ISO27001, etc. etc. etc.

The successful pattern I've seen is someone around VP level in an existing industry leaving their current company and grabbing some engineers to build their idea. Maybe because their idea is great, or maybe because they're stuck at that level and can't advance further without leaving. But either way, they generally have some contact with their peers at other companies in industry so when they go pitch their product, they're much more likely to succeed than any random asshole off the street.