Hey @Abigail J Steinert & @Steve Vaughan,
to answer some of your questions. When someone is an avid flipper, they usually have trusted capital partners if not a few great relationships where that pain and risk are very much reduced. Also, I would love to clear up the stigma that obtaining capital partners is painful and risky, which is in fact not the case. Just finding the right partners is difficult.
The following will elaborate on the above and answer more of your question.
See, it's an even bigger risk to have your money tied up in a deal than to pay some fees and interest on capital you are lent. Yes, you might lose out on a couple of grand here or there, but this is also a business that requires speed, and having a lot of your capital tied up in one deal will slow your scaling process.
To add, when it comes to most lenders, they will want you no have some equity in the deal. With that, you are going to need that liquid cash. If you waiting for the return/to pull that cash out from another deal, you're going to lose time and most likely money.
I hope that answers your question. I can go into more detail, but this is basically the reason.