Lemmy UI is very easy to use, and fast too. Also, I like the concept of federation (though I have no plan in hosting one) and the fact that the community has been very welcoming so far also help with me being able to enjoy browsing Lemmy.
Of course, there's the obvious problem of lack of content but if the subreddits that I usually lurked on have fully switched to Lemmy then I would have 0 issues with fully switching to Lemmy regardless of the lack of content.
I know you probably have seen a lot of answers from others already and my answer would probably be the same as others (for obvious reasons) but I am going to answer anyway because you told me not to lurk. Please note that I am not an expert (or even somebody who knows much about business) so don't expect my answers to even be half correct.
If by profitable you mean "not making a loss" then probably yes as long as if there are enough donations to cover the expense of running the server.
But if by profitable you mean "making enough money to be sustainable long term" then my answer would be most likely not because it's not designed to make money (unlike ahem...certain platform)