Nope. Nope nope nope nope nope.
They were speculators in a bubble market. It didn't matter what percentage of their life savings they used. If you feel sorry for someone who purchased a $300k taxi medallion which had an intrinsic value (the total value a medallion can be used for rental to taxi drivers over X years) which is far less, you are enabling such behavior.
You also have to remember that the more distorted the medallion market, the more the average taxi driver suffers. Taxi drivers, by and large, rent time in a taxi or own a car and rent the medallion. They haven't been able to afford their own medallions for decades, if ever.
Taxis had a "monopoly" on unplanned fares, but "black car" and limo service was competition (and, therefore a price ceiling). The more distorted that the medallion market, the more the other competing services would chip away at their business, diluting the value of the medallions. I'm glad that a product like Uber/Lyft was able to destroy the price floor of medallions.
I'm somewhat saddened that taxi drivers are losing that means of making a living, but it benefits far more people in the US to have a cheaper means of transportation. "Concentrated costs but diffuse benefits." It's similar to the way US textiles, steel, cheap manufacturing have suffered under globalization to benefit the average US consumer household, which saves for more than $2000/year after China joined the WTO.
NPR's Planet Money did at least one episode[1] on "The Taxi King", a guy who built a house of cards by leveraging the equity in some of his NYC taxi medallions to get loans for others. After Uber started to erode their monopoly, the medallion market popped and he's begging the state and federal governments for a "bail out". I could care less about this human piece of trash. Obviously, "the average" taxi medallion owner probably didn't own dozens of them, but I still can't find much sympathy for someone who invests in a bubble product created by a government-mandated monopoly that should have been disrupted decades before it was.
[1] http://www.npr.org/sections/money/2015/07/31/428157211/episo...