A few thoughts

What is the "proven track record"? In startups, "customers" are NOT it? Startups with customers fail all the time, all you have there is some evidence.

"The only question is whether the idea can be scaled profitably" -- No. Not at all. In fact, Profit is a NOT something startups should be chasing. Ever. Profit is for public companies in which shareholder price is tied to profit. As a startup, profit means you're paying taxes with revenues you could be using to invest (instead of relying on investors). https://seobrien.com/do-startups-not-need-to-be-profitable

The only questions (to VC) are:

1. Will you fail?

2. Can you and will you exit?

3. Can you deliver a 20x return?