What this really means is you can buy a Catalina 22 for $2-3K, dump a lot more money into it over 1-2 years, sell it for a portion of what you put into it, and have had the opportunity to sail your own boat and learn a lot about fixing up and maintaining a boat that you do not intend to keep.
Good advice. My partner and I did something like this, but be careful about over investing and/or over capitalising. After some initial lessons we looked around for a second hand fibreglass boat and eventually settled on a 1981 vintage Compass 29 (29 ft masthead sloop). An Australian boat similar to the Catalinas and Columbias of that size and vintage.
We chose her because she was in very good condition inside and out, and we paid for the privilege. However, even on the best kept 27 year old GRP boat there is a lot that is "tired" and old and we have spent quite a bit of cash so far in unexpected upgrades and repairs. While I love the boat and we have learned a great deal about systems, maintenance and repairs etc. (and had a lot of fun sailing), it has been an expensive way to do it.
In hindsight I sometimes wonder if we would have been better with a smaller boat - say 22-25 ft - that would have been half or a third the price and a smaller ongoing investment. In any case, buy a small keelboat so you are learning on the "real thing".
If I could do it again, I'd start by joining a local club and gaining experience by crewing for others, and meanwhile I'd keep my eye open for a sound boat in the 22-25ft range that needed a bit of TLC as my first yacht. You might also find that contacts through a club could get you leads to boats for sale that might otherwise never come up.