If you get acquired you almost always have to stay on for 2-5 years.
Having worked in M&A / financial due diligence before this, acquisitions are like an anal probe; they're never clean, simple or quick. They're sloppy, tedious and unpleasant. It's sort of similar to raising money in a sense that it's very possible that real work is put on hold for months. Ugh.
And the other thing is, I'm just a big fan of events and helping people have fun. When people tell me they used TicketStumbler and had a great time at X concert or Y hockey game, or a Dad comments how he took his son to his first baseball game, that means more to me than any dollar amount.
If the offer was e.g. $500M cash, "we're not for sale" would simply become "sale".
You don't have to believe me, just know that money does not equal happiness and in my humble opinion success is the amount of life you control.
I'm honestly not trying to be rude by saying this, but it's hard to believe that your ultimate goal in life is to sell tickets to people. If it is, more power to you, seriously, but isn't there something else you want? Something that TicketStumbler is a means to achieve later?
PG and Co. are already aware of all of this.