What's one piece of advice you want to give to founders who want to invest in community building?

all the best to your project

Community building takes time, so you should be patient. You can growth hack your way through it, but that would result in a sub optimal community with low engagement

Don't delegate it to a community manager. Manage it yourself and build your personal brand.

Invest in (finding and keeping) a good marketer. Honestly. Building a community is one thing but don't forget that with the community comes great responsibility to satisfy its needs and bring values. Marketers are there to research, understand, predict and help form and serve the market. And good marketers are also psychologists in a way they communicate with the community in a way it's living and growing organically (with WoM).