Bitcoin is not an investment, Bitcoin is savings. When you have excess fiat currency that you don’t plan to spend anytime soon, the best thing is to convert it into Bitcoin for the long term. Bitcoin is a hard and healthy form of money, like gold, but even better and harder than gold.
Mate Bitcoin is an investment because the value increases overtime so if you want to save your money you can go to the bank but for any money you own in bitcoin and you do not have any plan of using it in the short run, it is an investment because it is expected to appreciate in value. It's not even about having excess money in Fiats that you will begin to consider owning bitcoin, just with the little you have you can be investing from time to time till you grow a huge stash in your portfolio. If we go by that mentality of waiting till we get excess Fiats before investing in bitcoin it means that only few people will invest because a lot of people don't have excess money. Bitcoin is digital money so i don't think we should call it a hard currency, after all it's not a stablecoin.