~다가는 means "if you keep on doing ~~ like that, you will end up ~~ing"
그렇게 술을 많이 마시다가는, 위에 문제가 생길 거예요!
(If you keep on drinking so much like that, you will have a problem with your stomach!)
그렇게 돈을 쓰다가는, 거지가 될 거야.
(If you keep spending money like that, you'll become a begger.)