VOLATILITY: when talking about volatility in cryptocurrency this simply means unstable price within hours or days making them risky investments.
SECURITY: you have to be really careful and mindful of your wallet and keys, it is very important because once stolen or lost crypto assets are sometimes unrecoverable.
LACK OF REGULATION: while decentralisation is a benefit the lack of regulation also open the door to fraud scams and market manipulation.
SCALABILITY ISSUES: some network like Ethrerum and bitcoin can become slow and expensive during high demand.
LIMITED ACCEPTANCE: despite how growth, most businesses don't accept cryptocurrency as payment.
USABILITY: we the newbies find it so difficult to understand and manage cryptocurrency safely.
All of this are good points made OP, as a newbie with thus level if awareness, you are most likely going to grow at a good speed much more than others probably will a s newbies considering you have a fair basic knowledge. I'm going to highlight a few of your points as they got the most fo my attention.
Regulation is one core factor that even propelled the creation of Bitcoin, it's decentralised nature has got too many merits than demerits such that for a fact we can say it's too advantageous to think about it's disadvantage, it's decentralised nature has also propelled and strengthen its ability to fight inflation as it may have lost such ability if it were centralized such that it could be completely regulated, even the scalability issue you mentioned is actually a subtle tool to fuel volatility upon which cryptocurrency gets to build and maintain value, so literally all of this put together positions cryptocurrency generally to be valuable enough to be investment worthy almost all round.