The original generation of SSDs were pretty limited in lifespan, but TRIM was invented (also known as "wear-leveling") to make an SSD's lifespan competitive with that of a typical HDD spinning disk (and in some aspects longer-lived).

From a mobile-computing perspective, an SSD means longer battery life as well since you're not spinning up and spooling-down a typical HDD motor each time you want to read or write data from/to a disk.

And yeah, replacing an HDD with an SSD is a serious upgrade, even for older computers, since nowadays the CPU and RAM speeds of a 4-year-old computer aren't too much different than latest/greatest, but the I/O speed-up by going to an SSD will actually make an older machine somewhat competitive with a newer machine that uses a spinning HDD.

All that said, if I were buying a new machine (and later this year I may), my big focus will be on the GPU, full-stop. In CG, even the somewhat older CPU/RAM/SDD rigging will be more than adequate, but the big diff is in having a badassed GPU. This will speed up your UI if you're crazy enough to enable a GPU-hungry preview mode in the workspace, but the big diff is in cutting down render-times. If I get a laptop that replaces my current nVidia 1060 GTX @ 6GB RAM with a 2070 GTX @ say 12GB RAM, my render times would likely be cut in half, if not cut it down to an even smaller fraction.

(Example? Even now, I can dork around with the NearMe meshes in a simple scene w/ iRay preview in DS, and the render times are laughably tiny now, and the preview results are to the point where I could almost just take a screenshot w/o running a render and it would have the same level of quality considering their toonish skins.)

Anyrate, yeah, sink your ducats into the GPU... biggest, meanest one you can spring for. If you can get two and connect them viz. SLI or Crossfire, do that.