Aviation is a pretty expensive hobby to get into nowadays. You're looking at $10,000 just to get your private license. This really limits the kind of people that can get into it. And the opportunity cost for those people to take 2-3 months off for a stunt like this is really high. Never mind the time that it would take to prepare for it.
On one hand, you have a lot of folks that get into it as a career, so after their initial investment (mostly folks get money from their parents, some take out loans) you spend a lot of time teaching so you can reach the 1,500 required flight hours to become an airline transport pilot. These kinds of pilots are more interested in starting to earn a living rather than take months off to perform a stunt like this.
On the other, there's a good number of older, wealthier, folks that are near or at retirement age. These kinds of pilots aren't the kinds of folks that would be able to sustain months of endurance flying and living.
Then let's look at the costs. Cessna 172s are still being made so we can compare prices. In 1960 a 172 cost $9,450[1], which is roughly $87,000 adjusted for inflation. A new 172 today will cost you over $430,000! A lot of this price increase has to do with the exorbitant cost of insurance for manufacturers beginning in the 1980s.
Just for fun I also looked at the gas costs, they weren't as high as I initially thought they would be. There's not many great sources besides anecdotes that I found, but aviation gas (avgas) was around .30c / gallon in 1965 [2]. A 172 in cruise will burn around 6 gallons per hour, so in 1965 two months of continuous use nets $2,500 ($23,000 adjusted for inflation). Today avgas is almost $5 / gallon, so that's over $40,000 just in gas costs.
[1] https://en.wikipedia.org/wiki/Cessna_172#Variants [2] https://www.pilotsofamerica.com/community/threads/avgas-cost...