[jedberg]

I don't see this as any different than a founder who is also an angel investor, which many successful startup founders are when they go for their second company. They even cross invest.

If you look at the YC founders who have exited and gone on to found a second company, many many of them are also investors in other YC companies, sometimes even from their own cohort, if they did YC again. It's pretty common.

Diversification is a smart move. In this case a founder with less capital is investing something they do have, equity in their own startup.