Understanding BRRRR method

[Nicholas Weckstein]

I was just reading a post on here about the BRRRR method. It got me thinking. I need to understand how it works better. I know what it stands for and I get the process but I could use some clarification. So you buy a property at say 45k ARV is 100k The rehab is going to cost 30k Hard money lender lends on a 75% LTV So it would mean you need 25k out of pocket for a down payment if the ARV is 100k. Plus closing costs. You finish the rehab. You cash out refi 75% and take your 75k. After paying back the hard money lender 40k purchase price, and 35k rehab....your left with 0$ and a property with a mortgage. What am I missing lol. Also what about the issue with DTI. At some point your DTI would be o high to continue refinancing. I guess that's when you just sell for a profit and just flip until your doing it with all your cash ?