Thoughts don't become things; thoughts ARE things.
Consider the sunlight. You may see it is near, yet if you follow it from world to world you will never catch it in your hands. Then you may describe it as far away and, lo, you will see it just before your eyes. Follow it and, behold, it escapes you; run from it and it follows you close. You can neither possess it nor have done with it. From this example you can understand how it is with the true Nature of all things and, henceforth, there will be no need to grieve or to worry about such things.
You need to tolerate all manner of characters for your own good because, you cannot force people to change and even if you have to, you cannot change everyone.
It is in the nature of things that something when started cannot be reversed. Like getting attracted to someone. When the feelings are strong and the fire is lit then nothing can be ever reversed. So don't start the fire if you are not ready!