Two things:

1) If you have a really secure password (numbers, upper case, lowercase, *and* special characters, no common words, more characters the better) the chances of you getting hacked are incredibly small. Like incredibly small.

2) If you have a strong password but link your login details to other networks, that is where the trouble is.

PSN has known security issues. There was a huge crisis a few years ago when it got hacked and everyone's credit card details were at risk. The only counter-measure is to use a strong password and thats it. I even think getting a security token is risky, which is why I wont buy one. The only database/network that should have my account information is this one. I refuse to put it anywhere else, as I am at the mercy of that network's security.