Of course there are people who fake their photos and most try to make them appear more appealing than the situation they took them actually was.
Nevertheless it is also the truth that some are true to a certain degree and that not everything is fake. People travel to adeventourous and georgous places, people have fun, people meet interesting people, people have a wonderful time.
But I would assume that at least most of those people are not on instagram.
Instagram or any similar social platform is serving the same purpose as the "Status" pictures on whatsapp do: Showing other people that you are having a good time. Because if you are on the "winners side" more people feel attracted to you. It is the hope to reduce the bad times and neglecting parts of the truth that is making such platforms successfull. It is feeding on the fear to miss out the sweet things of life, and motivating people that are scared to not be part of those who have access to those moments.
Under almost every photo you can write the sentence: "Look at me, I am not missing out. Let me be part of the group of people that is enjoying life and be successfull."
That's why I assume that those who really are successfull don't need those platforms: they don't need to advertise for themselves or delude themselves and others.
They simply enjoy their time and if they take pictures and videos they only share them with their close friends or those people that were part of the situation when they took them. In order to remember that life can be good when they feel bad. Because they want to last what will never last forever.