Well said OP.
But to answer your question... Because capitalism.
Every single message we receive throughout our day in almost any context is that we must consume, therefore we exist. And people feel FOMO if they aren't consuming. This pressure is built inot advanced economies, but most prominent in the US and Britain. Every little thing you do costs money.
I come from a culture where a lot of things are free most of the time, e.g. parking, visiting nature, cultural experiences, and excessive consumption or wearing visibly branded items or driving a showy car is looked down upon. It's a much easier life.
In my 20s I had a lot of financial means and consumed a lot, especially in terms of excessive travel, experiences etc. Nothing really satisfied me, it felt almost like a hamster wheel of needing new stuff, new experiences, upgrades.
In my 30s I've put the money away into savings and assets and live a much simpler life, walks, coffees with friends at my place, exercising outside, reading in the sun... I'm a million times happier.
Consumption is very addictive, spending money is addicitive, and in the UK every little thing is heavily monetised, from the moment you open your eyes. It's very hard to step away and detach from that lifestyle, it's very normalised, and so people spend-spend-spend.
Just the way our society and social programming works.