It is not logarithmic, but rather linear, if you concur with the old-time experience.
For all us old-timers here, we remember the simplified anecdotal guideline casually referred to as the “Rule of Fourths”.
This was an inverse relationship that had its genesis in hi-end audio.
Simply put, once you chose to further upgrade while you now play in the high-end gear sandbox, upgrading further with a performance improvement expectation, generally required a four-fold dollar expenditure to get a 25% step-up in audio performance.
My take:
Because upgrading while striving for system synergy is a difficult and variable journey, throwing just money alone at it may parrot this homily and provide merit, …but … it still may not necessarily satisfy another parallel time-honoured adage:
“Price is what you pay. Value is what you get.”
- Warren Buffett