Those not as strong as you should be beyond their threshold and unable to keep up with you. If the pack thinks you are going for a preme they may try to stay with you, but if you keep going, and no one is on your wheel you may get away. Once the pack realizes that you are not going to let up, it may be too late to catch you. Or - if others are going for a preme, attack right after the preme just as the other riders sit up. Or - have a team mate attack, after the pack chases him down, and right as he is caught, you attack.
Wind discourages others to chase.
If your timing is right, it can be advantages to attack on the tailwind side of the course. Just as the pack would normally get organized they are slamming into a headwind. The headwind can delay the pack from organizing a counter to your attack. A break in the last lap or two can work, but that is when the pack is winding up, leadout riders and sprinters are at the front and no one wants to let anybody get away. Riders are no longer fresh and most are not too fearful of a solo attempt -because they think it is too far and that there is still time to chase.