I just got started with the industry last year, I was on the ground for the summer and was let go for the winter. I was given the opportunity to fly this summer and was able to put in almost 250 hours, I have since gone back to the ground with still the opportunity to ferry machines and go do some rev time if it comes up.
Coming out of school with 100hrs and expecting to be on the flight line is a pipe dream, you must get on with a company and do what it is they ask of you wether it be sweeping, delivering fuel etc. for some time before they will give you that chance of building time when they eventually get a position you can fill.
That being said with the amount of people the "puppy mills" put out every year there cannot be positions available for all of them, those with the determination and drive may find a slot eventually with patience and luck. But the ones with no patience and no luck may never get their chance and give up. It's a matter of chance wether you are able to make it in this business in the beginning and I think it's really just a roll of the dice.
In the end I think it boils down to perseverance and be being in the right place at the right time and there isn't much you can do other then hope for the best and plan for the worst.