There are many celebrities who release their own NFTs, but actually, I don't think that it is a very good investment. If this picture (video) is not backed by something, most likely you will not sell it on the secondary market. Sometimes such NFTs give you an opportunity to have an appointment with this famous person or get tickets for concerts with a discount then, it is better, but still, I would rather not buy such NFTs.
Yes right if the project or your NFT is one time hype then what would the holders get after they spend huge funds for them? The market is now against those projects which are just jpeg images or does not have any utility to serve in the market as they can't sell it later on at profit and they will keep dumping to some below levels.
Talking about celebrities there are many who are investing in crypto market these days but at current most of them are jumping into NFT space to make high profits within short period.With time many others will also reveal they hold crypto.