Once you become an adult, there’s something you can stop doing, but most don’t. It is important to know your *why* – the motivation, inspiration, reason that compels you to pursue the big goal in your life. It helps you to understand why, but you do not have to justify it to anyone else.
Others will ask, press, and many will get frustrated if you do not answer them. They can. Let them. Your why is personal to you. Everyone else will judge it and directly or indirectly, try to talk you out of it.
Most people will chip away at your why, question your motive, or flat out tell you that you are wrong. Even the well-intentioned will tread here. It is human nature. Under that pressure you forget, it is YOUR why, not theirs. Some of your critics might be right. It does not matter. You are the one who lives with your why, and as an adult takes responsibility for it and owns the consequences, both positive and negative.
If you are pursuing your wants and desires, that is sufficient reason. You may fail, you could be misguided, perhaps a touch delusional; or you could be a brilliant pioneer. Neither matters.
All that matters is that you pursue your why because you have decided you WANT to.
Congratulations, you are starting to act like a leader.