Whether you realize it or not, you are playing with scared money when you have too much of your roll at the table, which translates into playing bad poker. You HAVE to play with a stack you can comfortably lose, or else you're just not playing your best.

I never bring more than 10% of my roll to the table, and most here will say it shouldn't be more than 5% (20 buy-ins for cash games) if that's all you've got to play with.

Also, $10NL and $100NL are entirely different games in terms of opponent skill levels. If you MUST take shots, the highest you should be going is $25NL. Otherwise you're just asking to get your ass handed to you.