I wanted to tack on to Jason's point above as it's something I think about quite a bit.
There are many "types" of smart, and I think a bit key to building a team is getting people that are smarter, or better, or whatever, in the areas where perhaps you are lacking. A smart team is made up of people who share complimentary, but differing, skill sets and interests.
For example, say you're building a design team. You've got a great PM person, a couple very tech-minded designers, but you're looking to add some more talent. You might look at designers who have a way with words, or a lot of experience doing research, etc. as opposed to those who are technically strong. It's not always about leveling up, diversification is very smart.