Curious, what was doing your friend, who is ready to take over and lead? Why not switch sides, take over his functions, and offer your stake for sale during the next raise at that valuation?

Why not offer your stake to the company’s investors at the previous valuation?

A pivot, by definition, means turning away from the original course of the business.

If you were really motivated by the previous goal, and you're disinterested in the new goal, why stick around?

I've seen companies pivot from "we are going to solve plastic trash recycling using automation" to "we are a trading platform for bales of plastic trash" - much more achievable, but much less interesting.