The replies already here have touched on the most important factors and why they matter (it's open source under AGPL and it's decentralised, the core devs are ideologically anti-capitalist so they won't go public or sell out to advertisers, the users are the primary stakeholders)
But they haven't mentioned an issue with this question: we are a community. What could WE do to about becoming the next Reddit after a decade?
Most important? Get involved. Acknowledge that volunteering and donations are powerful! The best thing you can do is to help the devs, whether it be coding, translation, documentation, web design, or the many other things that help this place thrive. I see all these posts saying "Lemmy should make onboarding easier!" as if approximately two people are there to do all the work.
I'd say it's a mindset of coming from sites where you don't have the power and the only path for things to happen is complaining to the higher-ups. Being open source and community-driven are things new users need to understand. We may well be their first experience on a non-for-profit social media platform, where we don't have a designated full-time tech-support team, or a professional dev team of dozens.