Here's the problem: You get a groupset of components that you happy with (for me: Shimano 6603, 10 speed). You know that in just a short time this group will be replaced by all manner of new electronic, hydraulic, etc. stuff; and your parts are now obsolete and unobtainable. So, you need to start spending your money stockpiling all of your parts that will wear out.

If you have multiple bikes, stockpiling multiple groupset parts gets mighty expensive and complicated. So, I keep Shimano 10-speed triple groups on my 3 brifter bikes, and I keep Campagnolo Racing T parts on my three 6-speed friction shifter bikes. Now I have a parts bin that can service the 6 bikes.