Sometimes...not in those two specific cases in my opinion. Pretty vague question/concept. Some people enjoy fixing up and riding old bikes, some people prefer single speed and therefore don't find normal drivetrain expenses worth it, some people are fat and need to spend more on heavy duty wheels, some people find reason to spend a lot of money to ride really light bikes, some people spend similar amounts of money to ride titanium ones...Spend what you can justify to get the end result you enjoy riding.