Comment by pejrich

It's not that simple. The odds are always stacked in favor of the hacker. It's like saying, "why not just make a prison that's impossible to escape from". You can make a prison very, very hard to escape from, but you have to shut off every possible way someone could try to escape, whereas someone trying to escape only has to find one vulnerability, once. It's much harder to plug every possible hole in a complex system than it is to find one point of weakness.