Who is 'they'? Bitcoin and how you take care of your overall security are two different things. Nowadays viruses are more than ever focused on stealing people's crypto currencies, and at the same time, hackers constantly try to find a weak spot to exploit and empty hot wallets of services. If people with your mentality just assume that nothing can happen to their coins just because it's Bitcoin, they likely will find out how important their own security measures are when things go horribly bad for them (coin loss as result). At the end of the day, people only learn when things go wrong, unfortunately.