i agree 100%. long story short my dad, who rode around on an old trek forever, bought a used cervello that retailed for 4 grand off an IT guy who wanted to run with the big dogs on the weekends. Dad paid 1,500 because the bike didnt make IT guy fast and he couldn't keep up. Later that year the CF frame cracked, he had IT guy send it back to Cervello and he got next years model.
he had that trek 300( bought used as well) for probably 15-20 years, rode weekends and days after work, and did all sorts of sponsored rides. he kicked ass on an obsolete bike for years... its about the rider not the 100g shoes, speed play pedals, glasses, lance arm strong helmet, live strong bracelet, the tires, the bike or the "prework out drink" .
Just like any hobby you can spend as much or as little as you want but in the long run its not going to actually make a big difference. Diet, general health and fitness, and TITS (time in the saddle) is the best investment.