Venture capitalits (VCs) fund companies with the expectation of having very high return on investment. These companies that borrow a lot of money have then the expectation of hyper aggressive growth in order to monetize a huge market later and give enormous returns on investment to such VCs.
Often, for those reasons, they make the product free and hire very aggressively, in order to maximize user acquisition and quickly building a product.
After such growth, they find themselves having to find alternative business models instead of just charging people, because if you charge users for something that was free before they will leave.