Knowing that there was a tech bubble or a real estate bubble was the easy part. Many people lost massive amounts of money with this knowledge as these bubbles continued much longer than anybody could have imagined. In the process they ran over most of the skeptics. There is now a similar unsustainable situation in sovereign and municipal debt levels that will eventually not end well.
While I don't take the situation lightly and constantly monitor the developments, I try not to let it effect my short term trading. I am willing to go long for a trade when my indicators are lining up, despite these festering issues. Might I get hurt when the excrement finally hits the fan? Hopefully, I will be able to recognize when we are at that point but its possible that I will get nicked. But its unlikely to take away all the gains from all the other times when the indicators lined up.
I would much prefer if we were in a healthy environment with more reasonable valuations. That would allow me to concentrate more on investing and less on trading but that is not what we are dealing with right now.