I had a knitting machine years ago, one of those fairly simple ones, and I have to be honest: I barely used it. The problem isn't that it doesn't work - it works just fine, and yeah, you get things done fast. But the thing is, hand knitting has its own rhythm, its own meditative quality, and when you switch to a machine the whole experience changes. It becomes more mechanical, less creative. Plus these machines have a ton of limitations: you can't easily do complicated patterns, change colors on the fly, play around with textures. If you love the process of knitting, not just the end result, the machine might bore you pretty quickly.
Then there's the practical side, which other people have already mentioned. If you're barely knitting right now - a scarf here and there, just to chill out - it doesn't make sense to invest. But if you're already someone who churns out three or four pieces a month and you've got piles of yarn sitting around, then maybe it could make sense as a complementary tool, not a replacement. The real test is this: how many weeks would you spend in front of that machine if you had nothing else to do? If the answer is "eh, maybe two," save your money.
One last thing: TikTok videos show scarves coming out looking perfect, but they don't show you the half hours you spend threading the thing, adjusting the machine, fixing knots. It's not really plug-and-play like it seems.