I don't think it is necessary for you to attach great importance to ()to college.

这里的to相当与介词。
介词+动词ing

attach sth to sth，把。。。联系上。。。或者说，认为。。。怎么样。~
sth是名词，going 变成动名词结构，才符合语法。

go to college 去大学
前面是介词，用going