Not really sure the reasoning behind your question... but its not a matter of affording. Its a matter of efficient use of my money.

Two $350 payments for nexus 5 and then a 5x along with 24 monthly payments of $45 for Project Fi equals $1780 over 2 years. Plus I get a fresh phone each year.

1 phone for $200 (after 2 year contract subsidy) over 2 years on AT&T with monthly payments being $95 equals $2480 over two years.

After my contract was up with AT&T, they gave me a promo to lower my bill to $65, but to keep that rate I had to supply my own phone (meaning no subsidy). So it was buy a full price phone and keep $65 payments or take the $200 subsidy, 2 year contract with $95 monthly payment in order to get a new phone.

No matter which way you shake it, it was was cheaper to switch to Fi and get the Nexus.

I wasn't actually planning to switch to a new expensive phone a year in (and I haven't), but even if I do the total 2 year cost after the Pixel (~2080) still beats the previous alternatives with the added bonus of being contract free. Plus, if I go over my normal 2.5 gb by a few MBs I pay pocket change. With AT&T that was an automatic $15 charge.