Wikipedia is the 7th most visited website in the world, more popular than Amazon, TikTok, even PornHub. It’s not funded by advertisers or other bullshit - rather through reader donations.
With that said, Wikipedia is still centralized content whereas Lemmy isn’t. Meaning there’s fewer expenses and pressure on any one instance or server to succeed. And if one instance or server doesn’t succeed, your access to the Federation is far from over.