an elder statesman of my club is a former mechanic for team gb. his advice was that high-end groupsets are to be avoided by the regular clubman if they didn't have bottomless pits of cash to spend. the top kit is designed for the pros, designed for use in a few races before the sacrifices made to save weight make the components unreliable.
i had a colleague who used to occasionally ride 40 miles in on a campag record equipped pinerello. he'd been through lots of rear mechs and a carbon crank and at one point the bike was off the road because he couldn't afford a record replacement, even though he could have bought a lower spec one for less money that would last much better.
my tiagra groupset is still going strong after 10 years, although the chain and cassette have been replaced, as has the front mech. shifters, rear mech and brakes all work as well as they did from new, and the bike it's has clocked up probably more than 10,000 miles over the years. shimano tiagra/105/ultegra offer a good balance of lightness, performance and durability; think of all the groupsets produced by the likes of shimano, campagnolo and sram - the expensive stuff is high performance but with a shorter service life, the cheapest stuff bomb-proof but heavy.
clean and lube at least once a week, and things will last longer, whatever they are…
