If you have a good relationship with your college roommates and you have received a formal invitation, generally speaking, attending their wedding is a sign of courtesy and respect. However, this is not an absolute situation, because everyone's situation is different.
If you are not close to your college roommate, or you have not received a formal invitation, it may not be necessary to attend their wedding. In this case, you can choose to send a blessing or a gift to express your blessing and blessing.
Besides, you need to consider your personal situation and plans. If you have the time and budget to attend the wedding and you think it is a worthwhile occasion, then you can consider attending. If you have other more important plans or schedules, it is understandable not to attend.
The final decision depends on your own feelings and judgments. You can make decisions according to your own situation and relationship.