The cheapest upgrade is usually the one that works

Small, targeted improvements often outperform the expensive replacement they were meant to precede.

There is a persistent belief that a faster computer must be a whole computer. In practice, the thing holding a machine back is often a single bottleneck, and relieving that one constraint returns most of the benefit for a fraction of the outlay. Owners who go straight to replacement frequently pay for a great deal of new capability they were never short of, in order to fix one thing they were short of. It is a common and understandable way to spend a lot of money for a modest improvement.

This is also why the sequence matters. Before accepting that a machine cannot be improved, it is reasonable to ask which specific thing is the limit, and whether that thing alone can be addressed. That is a fair question to put to anyone advising you, and a good adviser will welcome it, because it is exactly the question they ask themselves. Getting a real answer converts a vague sense of decline into a concrete choice with a price attached.

There is a limit, and it is worth naming honestly. Every machine reaches a point where each dollar buys less, where parts are harder to find, and where you are improving something that is going to need the conversation again shortly. Past that point, spending is sentiment rather than economics. The skill is not refusing to replace, it is knowing which side of the line you are standing on before you decide.