How is $1,000,000 a lot of money?

From here.

I fired off an email to Steve Jobs about this. I basically told him that if Apple had to have one must game on the platform that year, it would have to be Half-Life 2.

….

At some point Apple did meet with Newell, but I guess nothing came of it except that the project never could take off because of Valve’s insistence that anyone who wanted to port Half-Life 2 to the Mac had to advance $1 million to Valve.

How is $1,000,000 a lot of money? According to Wikipedia, Half-Life 2 had a 5 year development cycle. The original budget for Half-Life 2 was probably $15-20 million dollars, at least.

How is an advance that equals 5% of your original budget a lot of money?

If a publisher can not recoup 5% of the original development cost, it probably doesn’t make sense to port to that platform.