In each set of sentences, the second option is more grammatically correct: "To see the basketball match is my purpose for coming here." "To keep my body healthy is my purpose for doing exercise." "To make more money is his purpose for going abroad." In each case, using "for" is more natural and idiomatic when expressing the purpose of an action. Also, there was a typo in the third set of sentences; it should be "his" instead of "he."