The disadvantage of investing in bitcoin like you said is that you can loose everything if there's a problem with the investing, and if bitcoin fall drastically from the price you actually use in investing.You stand the chance to lose all your money. Bitcoin is unpredictable, it is volatile hence it may be worth $40k today and less than $30k in 24 hours.
Also it's risky, since transactions are irreversible, if you mistakenly send money to another account, it's forever gone.