I think you could be underestimating it.And it won't work.
Wikipedia crushed all the commercial encyclopedias that came before it for a reason. Musk has nothing to compete with it. What does he even want to do ? Make AI write articles ? People will just ignore an encyclopedia full of AI slop and hallucinations. Pay people to write the articles ? Too expensive to match the volume of Wikipedia even remotely. Use free conttributions but only those with a right wing slant ? That is just a second Conservapedia.
He has no selling point and, again, vastly overestimates his reach.
The only way for that to succeed is if gouvernments sabotage Wikipedia.
Firstly, a large number of ideological entities could preferentially use Grokipedia. They know it is biased... but that's the point and why they use it. And as they use it as source and reference, so it achieves a further reach. Then AI's scrape the websites using Grokipedia as a source, and so on. Then there are a host of lazy people who won't know or care about the difference between Wikipedia and Grokipedia, and a load of them will use Grokipedia just if happens to be the first thing they find, and again start filling the web with Grokipedia-based information and building momentum.
Then of course we can consider that internet search engines often privilege sources. Google search, for instance, gives Wikipedia a privileged access (it usually has a box to itself). But what happens if they switch to Grokipedia? What if someone pays them to privilege Grokipedia? (Wikipedia, let's remember, runs on donations and would not be able to compete.)
As for government sabotage, I would just draw your attention to the USA. Do you think Trump or some future Trumpist would be above threatening Google with serious consequences if they didn't favour what he wanted?