Because there's risk, it fluctuates, there's no guarantee it will always go up. People need to decide to what degree do they want to invest and be exposed to the risk and reward. Say someone decides they want 1BTC of exposure, and are contemplating buying an item of 0.01BTC. Would that really be a big deal? Small changes in the degree of exposure shouldn't be a financial problem to worry about.

Plenty of the bitcoin true believers have.

Everything you're talking about makes sense for investing in a commodity, not for a currency.