So you can piggy back on the CDNs that do the same until you can afford to do so, with the same performance. This isn’t a privilege only given to those cloud providers, anyone with a checkbook and a pulse can do it.
It is hard to directly compete on long-form video because of audience and content depth advantage Google has with YouTube.
There are successful niche players who are fairly large (like Vimeo or Twitch or even OnlyFans) who focus on specific markets that don't require social network advantage like corporate or smaller segments etc.
For general purpose media, creators are going to focus on the platform with most audience and vice-versa, very hard to break that.