As with all bracket games, the luck of the draw comes into play. I was on the squad last year when a kid from Wichita State rolled an 820 in team, and he won everything. I lost all $100 in team brackets that I invested, and shot a somewhat-decent 587.
The next day I decided not to get into any brackets, shot 1307 in S & D. I'm not so sure I would have won my $100 back in that squad either, as scores were high.
I guess my point is, $100 for me is a good gamble on team day...if I lose, I'm done, if I win some $$, I re-invest in S & D. In my 4 trips to Nationals, I'm probably down around $150 total. You'll see plenty of bowlers investing $1k per squad.