Can only echo the above... "anybody’s guess", "better ways", roulette ...
Who knows how long this electric stringed instrument "collectors market" will last or if electric stringed instruments will still play such an important role in music in 30 years time and if there will be an interest in and if such a high priced market for otherwise very standard used instruments will still exist.... It's partially fueled now by people who want a particular instrument they were not able to have in the past (or previously owned and want again) fair enough, but also a lot of it via people collecting for the purpose of banking on an investment.... the later a bubble which can quickly pop, the former something which the wheels of time will limit the market for.
If it is an especially historically important museum worthy instrument (e.g. a 1936 ES-150, a 1951 Precision, possibly even a somewhat less popular Gibson 1953 EB-1 etc), it will probably be worth something long term. Any thing else from the factory line, who knows. Synths, violas, kazoos, a vintage cell phone music composition app, didgeridoos or dulcimers may be the popular "in" instruments in 30-50 years time. With the current reduction in live music venues, who knows if amplified electric stringed instruments will persist long term as the main choice for "popular" music.
To avoid hurt feelings I'll use an E2 6 string guitar as an example. When the current collector's market considers an early 1960s, common, student grade, laminate (aka plywood) Gibson ES-125TCs as "collectable", you really do have to wonder.... (I do like, enjoy, play & have an ES-125TC - was my first electric guitar & picked one up cheap years ago for sentimental reasons mostly, but they really are not anything particularly "special" or to write home about. They are certainly not better than a Heritage 525 or possibly even a CN Loar 320T (have not tried one). When I see the current prices I can only shake my head... and these are comparatively inexpensive in the collector's universe).
I'd choose an instrument to play and enjoy, not as a "possible potential" investment.