When DDR4 was obtainable for maybe $1.50-$2.00/GB (or less if used/open box, picked up 4x16GB for ~$70), it was trivial to have 32-128 GB.
Applications will generally attempt to use more memory if more is installed. But another big thing is that capacity that isn't being actively used can be filled with cached data. So I have about ~18 GB used and ~29 GB cached, with ~17 GB free. 54 browser tabs open. And that's a good thing.
If you have more RAM than you need, you aren't touching swap/page file (or at least not frequently), and that's going to be better for the longevity of the drive.
It could take 2-5 years, but we'll see that kind of pricing again, and hopefully below $1/GB later in the 2030s. And when memory is cheap, you should buy it up. Even for e-waste. Quad-core with 64 GB? Just do it.
There's a lot of laptops with only soldered memory, but I made a point to buy a cheap Lenovo with a modern chip (i3-1315U), 8 GB soldered RAM, and an empty DDR4 slot. I upgraded it to 16 GB, it can go to 24 GB officially, and likely 40 GB with no trouble.
After we move past LPDDR5X/DDR5 in laptops, memory upgradability could be questionable. SODIMM is dead after DDR5 according to JEDEC. The new CAMM form factor could be used for DDR6 (or LPDDR6, but they are not interchangeable in the same system). But time will tell if CAMM remains a niche or becomes widespread enough to be found in the laptops you want to purchase, and obtainable at reasonable prices. Laptop makers could trend more towards soldered memory. It will become a concern before consumer DDR6 is available, since LPDDR6 is technically unrelated, already coming to laptops in 2027, and will offer much higher bandwidth than DDR5 SODIMM.