That makes it difficult, but not impossible, for hackers and their ilk to find them. Broadband connections, on the other hand, usually get permanent IP addresses because they're always on. That, in turn, makes them easier to find. That wouldn't necessarily be a problem were it not for the fact that hackers are smart, and they're always finding tiny points of entry and new ways to access other computers. That's why you need protection.
Some hackers go after everybody.
They scan for IP addresses and attack everything they find. Other hackers try to steal credit-card or sensitive personal information stored on personal computers. First, the always-on connection is one of broadband's major benefits. Second, it wouldn't help anyway. Most hackers use programs to do their work for them.