The biggest disadvantages of bitcoin is that bitcoin can be stolen by anyone in many ways. Bitcoin service providers can be hard to trust, but even if it is, we must to trust bitcoin. You joined in the field of bitcoin then it means you trust it. There is a lack of acceptance, lack of protection because it is not considered as legal in most countries in the world.
I absolutely agree to that, but if you do not want to stole your bitcoin you must put your password or private key in a safe place so that your bitcoin will be not stolen by anyone. In addition, one the biggest disadvantages of bitcoin is you can used in offline transactions and offline market.