As for the algorithm - in modern times all these companies driven by advertising. The algorithm works as a means to enable more effective advertising, and especially native advertising. It also likely helps build more effective profiles on people which can then be further monetized with advertising. I'm certain it increases addiction, but that's like saying that the special jingles and bells and whistles on a slot machine increase addiction. You're just adding to an already highly addictive baseline.
I also don't think TikTok really 'won' because of their algorithm. Facebook is now for parents and grandparents, while younger people moved onto other services to find their own place. I think the same sort of view of a service being dated became true of YouTube, even moreso as it moved more from YouTube to CorpoTube. Most, if not all, alternatives tried to be YouTube but with less content and worse CDNs. TikTok actually tried to put the 'You' back in 'YouTube' and caught on exactly like YouTube did back in the day. Go figure.