These are the things you often don’t take into account.
When you purchase travel tickets you spend in hotel, transportation, food and fun experiences. When you buy a car you have to add gas, insurance, repairs and maintenance, emergency cases, tolls, cleaning. When you buy a new camera you need to spend on lenses, straps, cases...
You get the point.
When you buy one thing, it’s never one thing. There are most of the time complementary hidden expenses.