Would the dentist really lie to me about this?

That sounds extremely suspicious. I'd be looking for another dentist for a second or third opinion. I have a wisdom tooth that grew straight forward inside my jawbone instead of growing in normally. Every dentist that I've seen has insisted that I should have it surgically removed because it could cause problems in the future. My feeling is that I should have it removed when and if it did actually cause problems. It's been fine for sixty years.