Let us consider your points.
Mainly, if we would be taxed on our bitcoin investment then most probably the government find ways on them to make their regulations and made it as a legal currency. In contrast, many investors would have to make a secure standing and viewpoint for bitcoin and other cryptos. But, it is hard and very difficult to realize, given the situation and assumption to convince people out of investing in it. The very reason for this is the nature itself; since bitcoin is a decentralized currency then it no one could possibly control it. It is also hard to monitor and if the government would want to regulate its transaction and flow in the market - then "good luck" to the government.