Whoever gets there first reaps the most benefits - word for this?

Solution 1:

The idiom is "The early bird catches the worm."

"The early bird catcheth the worm." first recorded in John Ray's A collection of English proverbs 1670, 1678.

This has been shortened to "early bird" and "early riser" but it is a bit towards the colloquial and not exactly a technical term.

"Early adopter" has no value attached to it. You could be an early adopter and not benefit or gain anything (even worse, gain pain) from it.

Early bird has the problem of context, where it could just mean that you were someone who does things earlier than normal: an early bird special is for people who eat dinner before a dinner rush, for example, and not wholly about "benefiting from early adoption."

Long story short, there is no single term for "early adopter + one who gained from adopting early" aside from the idiom.

Solution 2:

In business, there’s the phrase “first mover advantage”, implying that the first company to set up in a particular field will do better than later arrivals.