If we were limited to just this star system, and built a Dyson sphere around the sun and then used that to power minds running as efficiently as possible, that works out to being able to support a population of about 2.5*10^31. This is the same as the population if every star in the observable universe had an earth-like planet with a population of a billion.

Admittedly, if you have FTL you could go beyond the observable universe, but it's not like we're limited to just one star system without it. We could populate the entire cluster before long.