I would imagine suddenly coming into a big lump sum like a lotto win or unexpected inheritance could have the effect you speak of, of people going a bit mad and forgetting themselves.
However, DW and I both grew up in families of fairly modest means. We weren't poor but for instance my brother, sister and I would have to take it in turns to have a 'big' present at christmas and we never had flash (or even new) cars or anything like that. If we went out for dinner as a family our parents would always be scanning the prices before ordering and stuff like that.
DW and I both had part time jobs through college and university etc.
However now we are in our 40's we are very very comfortable and make half a mil a year between us after tax so by most peoples' standards we are pretty rich. Because the change in our fortunes has been gradual, and has been earned through education and progression in our respective careers we haven't experienced any of the things you describe worrying about.
I remember once about 20 years ago DW changed jobs and had a £60k pa pay rise (which was absolutely huge for us then as we were nowhere near the salaries we are on today). The first thing she did was work out how much extra she could funnel into her pension and the tax implications, then started looking at the best investments for the rest. I think we celebrated with a bottle of champagne that was on special in tesco.
Don't worry yourself, it's money you've worked hard to earn so I don't think you'll go bananas with it.
A good tip is start with aggressively paying down any debts you might have like personal loans, store cards, credit card balances etc. Once those are paid down, you won't be accruing interest every month which will free up more money for you to keep.
Next work out the amount each month you'd like to save (make it realistic or you won't do it) , and take that amount out and put into savings as soon as you get paid, then you know the rest is yours to have fun with.