First, Satoshi created BTC as a currency. It is intended to be spent.
Well not really, if you don't need to spend it then there's probably not much point. A spending culture has been prescribed into a lot of people already, spending on something that's you're going to use or need is fine it's when you start creating waste that's the problem...
You spend inflationary currency because its value drops.
Second, if everyone HODL and nobody spends BTC, isn't this becoming just a pyramid scheme?
A pyramid scheme like the stock market?
Most things, realistically, become problematic when people have a lot to sell and choose to sell them all at once. Shaving $5tr off the US stock market for example wasn't $5tr leaving thst was already there - it was too many people selling for the order book to absorb (and if people collaborate or have a lot already, they can manipulate the price of things quite well).