As reported in this article Firefox (and also Chrome, Spotify and possibly other apps) have the habit of doing an insane amount of cumulative disk writes over time (just leaving the browser open with several tabs open for a day can result in multiple GB of disk writes).
To avoid wearing out an SSD, at least for Firefox there is an easy workaround:
Enter about:config
in the URL bar, then find browser.sessionstore.interval
and change it from the default (15000 msec) to a much higher value.
I set it to 86400000 (one day in msec), as I don’t really need the session restore feature much anyway - if you experience frequent browser crashes better choose a lower value, but definitely much higher than 15 seconds.
I hope there will be a solution for Chrome and other applications as well.