The Collaborative International Dictionary
Top out
Top out \Top out\ (Building) To top off; to finish by putting on a cap of top (uppermost) course (called a
top`ping-out" course).
Wiktionary
top out
vb. 1 (context intransitive English) To reach one's highest point. 2 (context intransitive English) To quit one's career during a period of success. 3 (context intransitive English) To complete the construction of a tall building, originally by putting on a "topping-out" course.
WordNet
top out
v. give up one's career just as one becomes very successful; "The financial consultant topped out at age 40 because he was burned out"
reach the highest point; "Bids for the painting topped out at $50 million" [ant: bottom out]