There are other important factors as well that, imo, will lead to faster adoption.
Firstly, the underlying demographic change that will happen over time. More tech savvy, bitcoin literate will be controling and managing wealth. It is not difficult for the younger generation to operate wallets in their current format. Most studies also demonstratw how the younger generation sees bitcoin as a better store of value compared to gold and are getting into investing thanks to cryptocurrency.
Secondly, the rhetoric around bitcoin and what it means is also important. Bitcoin to me is storing value or liquid assets in my own custody as opposed to a third party that uses it as cheap source of funding without offering any compensation in today's markets. Banks allowed ordinary people to store cash in a more secure way rather than in their mattress or safe and there was a value proposition in using a bank. That value proposition does not exist anymore. Educating people around this and how to safely and securely store value in wallet will lead to greater adoption.
Thirdly, reduced volatlity will lead to higher adoption and this is somewhat an x factor. Larger pool of capital in bitcoin along with varying investment and trading strategies will lead to reduced volatility in my opinion. This will be followed by greater business adoption i.e. further acceptance of bitcoin as a transaction currency. However, regulation and technological innovation has to move in tandem with capital infusion.
Regarding loss of funds due to errors, I am sure an insurance industry vertical can come up that allows one to buy protection in case such errors happen. Iphone came out 10 years ago and led to the creation of a whole new economic ecosystem and also changed the way we consume data. That is very much possible with bitcoin in 2 years, imo.