But then there are many aspects to the decision.
Reliability ?. I used to take the fleet cars to the garage for servicing MOT etc. It didnt take long to realise things like starter motors, alternators etc started going at 60 to 80k miles. A friend of mine has a Merc Vito van with over 300k on it. Last year he did the clutch, then the injectors went, then the fuel pump, then the water pump. Every time he told himself...well, that's the last major thing that'll go wrong . He spent over 2k repairing a 12 year old van but it was good in every other way so he didnt mind.
Boredom ? I tend to get itchy feet at 4 or 5 years, want something new, different.
Peace of mind ? My Astra was almost flawless for 70k miles, i'd had my money out of it, time to start again and hopefully get that reliability again.
All these things are reason enough, if it suits you. You pay of course, that's inevitable.
Or spend and repair and hope for the best. Each one has its pros and cons.