Apple says there are 248,000 registered iOS developers in the US alone on its job creation page. This number leaves out:
- Developers registered in other countries.
- Mac Developers who may not have iOS dev accounts.
- Development team members who use a single account.
Assume that represents just a conservative 20% undercount, that would put the number of devs world wide (as in "Apple World Wide Developer Relations") at 300,000 more or less.
Number of seats available at WWDC: 5000.
You do the math.
WWDC ticket holders are roughly speaking the 1%.