They have these often here in SoCal. Hawaiian Gardens mostly. There will most likely be more than 40 runners.
me that there will be a small contingent of players who mainly play ring games, but will take the free shot and will not rebuy. For the most part they will be gone by the first break. This won't bother them at all, they came to play ring in the other room.
The rest of the folks are prepared with an initial rebuy, and at least the big add-on. Of course taking that first dealer bonus is a must. Depending on your pocket money, you should probably be prepared for more than 1 re-buy.
At Hawaiian Gardens, there is the opportunity to go wild just before the add-on by offering up to 3 re-buys. And there are an amazing amount of players who will do all of them. Then the add-on, and someone who was short can be a contender instantly. These folks are not all fish, or gamblers. They see the opportunities and internally calculate that it is worth the try.
So, even tho this is technically a freeroll, in reality it really isn't.