Thank you ! Premium Bonds are a real oddity, and I think the way they are done is peculiar to the UK. They've been going for decades, and the actual rate of return isn't particularly great, but having a small chance to win a million pounds gives people the chance to dream.
Of course, when they were first introduced, a million pounds meant you'd never have to work again and would have enough to live in luxury for the rest of your life. Now, it's still a big chunk of money, but inflation over the years means it isn't life changing in the same kind of way.