Maybe in dollar terms, but assuming the business keeps growing: they have sustainable income, they don't need to worry about getting laid off, they don't need to play politics with leadership, and they can turn the business into passive income by hiring someone to take over.

At this stage they are a lifestyle business, its not hard to grow it even more if they get investments. If they can sell the business over $10 million, they already surpass what most corporate employees will earn in their career. That's a very attainable valuation in 2022 with a PM fit product.

And slave away for the rest of their lives?

I'm sure they're not killing themselves with work and I'd trade equity in plausible with any job