Doesn't the high resale value of Macs not make it worthwhile to hang on to your old one as long as possible?
Also why would you have to spend $6000? You can get a refurbished 16-inch M5 Pro with 48 Gb RAM and 1 Tb SSD from Apple for $3000.
That's funny, I bought the config you are describing, but with nanotectured 14" instead of 16 new in July from microcenter for 2700 after tax.