Here is my take from both ends of the spectrum. We grew up dirt poor, like very poor so pinching pennies was engrained in our family.
I went to a state school and back then was cheap. Lived at home. Left college with maybe 10K in debt. Went to state Med school and was also cheap back then. Tuition was 8K/yr. I was offered 30K in student loans. I took out the min to live which was 15K. Ate the cheapest food, lived in run down apt, etc.... Left med school with 100K in loans, 110k after residency was done. Paid that all off in less than 1 year.
BUT 2 wks before residency was over, I bought a brand new 2000 BMW X5 which ended up being a maintenance headache but that was by far the best purchase of my life. But still had the penny pinching mentality making 400K/yr.
Looking back my major regret was not taking out the full 30K in loans and living comfortably in a nicer apt, better eating, better experiences and getting a car that actually had AC in the Tx heat. I prob would have ended up with 200K in loans but would have that paid off in about 1 yr.
Now that I am FIRE and make more than I can spend, i don't even blink about "wasting" money. Instead of a 500/nt Hawaii rental near the beach, we do a 1k/nt right on the beach. Instead of $20 meals, we will do $100/pp for a nice experience. No more group lessons when we ski, its all private lessons. No more group tours, it is all private tours. Instead of spending 300 on connecting tickets, I will spend 600 on direct flights. Now, I still don't waste by going first class but not connecting is well worth the 300 but 1k more is not worth a bigger seat.
Its great to pay off debt and be financially in control, but don't be so tight where experiences/vacations become work rather than fun.