most everyone else has hit it here but I'll add that if your quick flipping than yes you are paying taxes and since you aren't holding for more than a year you are paying short term capital gains which are taxed at the same rate as ordinary income. Many are doing what i dubbed "delayed flips" where they do the BRRRR thing and then sell. When they sell later 1. it's at long term cap gains rate of 15% and 2. over the past decade with a rapidly appreciating market they are selling it for even more than what they would have gotten right away. So they make a years worth of rent and then sell for even higher profits.
Keep in mind, you pay taxes when you are making money. If you can buy a property for 100k put 30k into it and sell it for $200k even after closing costs, you are pulling in 50k of income. And if you are really leveraging your time by having realtors or wholesalers bring you the deals and contractors doing the renovations, you really aren't doing a whole lot of work other than signing off a few documents and writing a few checks. IT sure beats sitting in an office 9-5. Literally 2 deals like that a year, someone can make 100k income for 8 weeks of work.