Maybe they feel that they are good at endgames?
Steps to follow:
1) Don't give them trades that benefit them (don't place your pieces so that it is possible for them to trade in a beneficial way) and they will end up making trades that only hurt them (you gain a tempo developing a piece, they lose a good Knight for a bad Bishop or something like that)
2) Learn to play endgames well
3) Win those endgames
Follow those steps and you should win most opponents who use this strategy and you will end up climbing the rating ladder and it will not happen so often anymore.
Recently while playing 10 Min Rapid games I have encountered many opponents who blindly proceed to trade off most pieces and lo behold, the endgame begins in nearly less than 18 moves with 8 mins remaining on the clock. How do can one deal with this absurdity. I am pretty sure this is hindering my long term growth in chess skills and it's adjacent domains. Should I switch to 30 Minute Rapid time control to find more serious minded players? All suggestions and criticisms are appreciated. Wishing everyone a nice day.