That wasn't the original purpose behind creating Bitcoin, but unfortunately, it has become that now. People barely care about what it was created for, and they barely care about the properties it has, people nowadays only care about its value because that is going to make them money in the long run, so you are not wrong in saying that when you buy and save it, it is going to appreciate in value and give you profits, but we shouldn't forget about the use cases of Bitcoin as well.
People are never the same and the world population is big enough so with the minority are Bitcoin community members as either investors, traders, speculators and gamblers, they have very diversifying ways in interaction with Bitcoin and usages. Bitcoin does not restrict anyone on how people can use it, and it gives people freedom, privacy and anonymity if they want.
People can contribute different things but with whatever reasons behind, if they have demand of buying bitcoins, it's good for demand as Bitcoin market will have more capital inflow so the price would be supported by more buyers.
There is nothing wrong in spending Bitcoin, because when you spend it, you basically spend it based on its current value, and there is no need for you to think you are wasting it or anything like that.
People are free in spending their bitcoins but they must be careful with any activities with wallets, UTXOs, transaction broadcast as Bitcoin transactions are irreversible and if they made mistakes on chain, their bitcoins will be lost forever and no ways to recover it.