The Federal Reserve, the central bank of the United States, has been raising interest rates very aggressively for the past year and a half to fight inflation. This has ended a very long-lived policy of near-zero interest rates which has been in place since 2009, the Great Financial Crisis.

When you borrow money from the bank, i.e. to fund the operations of a money-losing site like Reddit, ultimately the interest rate you pay on that loan is affected by the interest rates set by the Federal Reserve.

While interest rates were near zero, investors in money-losing companies like Reddit could justify just borrowing more money to keep the companies going, as the money was cheap.

But now with higher interest rates, the investors in Reddit, and other money-losing ventures, can no longer afford to just borrow more money to make up for the money they lost last year, they actually have to show a return or at least cut the losses to a level that the investor will tolerate. That means monetizing everything they can.