Sure we all have some financial regrets, some mistakes and some perhaps listening to a wrong advice but what's the biggest purchase/money spent that you see as a totally unnecessary now/regret?

For me it's a year into my first well paying job, I was in my mid 20s and thought I deserve to treat myself to a car I always wanted. Mistake part was buying brand new, went into BMW dealership and when u saw that beautiful E39 M5 all logic went out of the window. Drove off with a car I paid over $105k only for it to be worth around $75k by the time I had my first oil change.

Lesson learned though, never sice have I bought a brand new car, rather I'd buy CPO/under a year old and save a lot of money. Spending $5 on a new car smell freshener is definitely better financial decision than paying $30k for the smell.