If you are looking at off the street to right seat on an A320/B737 it will come to about $100 000 in direct out of pocket expenses.
You will probably be looking at years in lower paid jobs and a few moves while you gain the experience most people have when joining an airline. This cost could be low if you get taken on fairly quickly and upgraded in a reasonable time, spend ten years in GA and it will be considerable.
Also factor in no pay for 12-18 months while learning.
Now compare all that with using your $100 000 to buy a property and getting a job as a train driver ,which covers all your training costs, pays a training wage and gives you around $80 000 annually after a three years on the job.