Stealing is illegal, blocking ads isn't. The FBI recommends you use an ad blocker.

If anything, ads steal from YOU. They take your time and attempt to get you to part with your money.

You're not obligated to support a business model based on theft, if you want to consider it that. You're not obligated to support any business model.

If it's allowed, then go for it. They can always switch to another business model.