There are many things most likely to consider whenever you're investing money in crypto..
These are:
1. Volatility of the Market.
2. They don't have the knowledge about crypto.
3. Negative news that they see or hear in social media/TV Media.
4. They were scammed and afraid to invest again.
5. Threats of hackers in the internet.
But users can also protect their computer from hackers by using:
1. Virtual Private Network for Internet Protocol
2. MetaMask Wallet
3. Not saving any private keys in your PC.
based on my experience the main most reason is they are afraid to be scammed because now a days many ICO is dissapear after the softcap/hardcap and its very alerting so thats why many people/users are just go for the trading risky but surely. But to stop investing many legit and great project need your money but be careful.