They give a lot of characters/vbucks away for free. I have a whole list of skins (including the 3 you mentioned) and have never spent any actual money on fortnite.
I can't deny they've made a crazy amount of money from convincing teenage boys that it's cool to buy outfits and play virtual dress-up. But compared to the must-have items of my youth at least you aren't excluded if you have no money.
If you wanna be able to play as Batman or Mr Meseeks or the dog from Adventure Time, that's $60 already.