Commerce, people conducting business want to conclude it and FOMO, ordinals (a sort of on chain layer 2) degenerates want to make sure they get their trinket, token, or jpeg. The next block may also have high fees, too. As fees peak people have to bump their fee with RBF or CPFP or wait a very long time for the fee market or die down. In general, high fees are a positive sign that bitcoin interest and utility is increasing.

If you need your payment to confirm quickly...someone might have sent a deposit to an exchange, or is trying to pay for a service they want ASAP. Most counterparties don't treat mempool txns as payments, so it's not "paid" until it's in a block, or in a block that's had some more blocks built on top of it.