Besides saving my bitcoin, I also spend my bitcoin by converting into cash because I need that cash to buy my daily needs. That is what most people do with their bitcoin. But yes, we can save or spend depends on our purposes so if someone wants to save their bitcoin, then they can do it. That will happens to people who want to spend bitcoin.
But if all people who own bitcoin don't spend bitcoin, I don't think that bitcoin can grow or reach all people because bitcoin will not moves. It will stay like the beginning when it's invented. By using it, spend or saving, bitcoin will grow until now, and in the future, so it could reach more people so they can help bitcoin to grow more than now.
The beautiful thing of BTC is the fact that BTC is not an imutable thing
You can use BTC to spend for you daily needs, I can use for investment, another person can use for pay someone in another country in minutes with a little fee, another person use to gambling online, a company can use BTC to offer a good investment to their clients and the list can continue
Every kind of situation helps BTC, there's no only one use to BTC