#1) it doesn't pay any dividends like stocks
It pays in capital gain which outperforms most other asset classes.
#2) risk of extended drawdowns which could cause loss of principal unlike in a real estate investment where the property only goes up in value
Real estate goes down in value as well. Real estate might not get you any capital gain also. The you pay registration charges and stamp duty and mutation charges (for land) etc. for each real estate transactions. Real estate has lost its charm as an investment in urban areas.
#3) unfavorable tax treatment since it cannot be depreciated like many types of assets can be when used for business purposes
That's a true challenge! In many countries, tax rates on crypto currency is very high. Also there's no way offset the loss as well. Which is surely discouraging a lot of people to use Bitcoin as an investment. I personally have not sold any Bitcoins since last 2 years due to a 30% tax treatment in my country. That needs to be addressed by the industry stakeholders.
These reasons do not really make Bitcoin a bad investment choice. Rather, it compensates us through capital gain. But different countries have different tax treatments which makes this investment either favorable or unfavorable for their citizens.