I would guess that every experienced entrepreneur and/or consultant would provide a different opinion on this question. I have been on all sides of this question and have started businesses at a variety of stages of life. As a young, inexperienced entrepreneur one has the advantages of not knowing what you cannot do and so you may challenge and overcome limitations imposed upon older more seasoned businessmen/women by their background, experiences and environment. That same predisposition to discovery and adventure allows a young person to see and do unconventional things in unconventional ways. This along with the interest of lenders, investors and promotors in encouraging young people to create businesses for the future can deliver another advantage. The final advantage I will address here is that when you are young and inspired it seems easier to create support from peers either because they are encouraged by your challenge to the status quo or because they have not established personal and business networks and believe they can grow with you. Disadvantages to the young are lack of credibility, resources, and connections. There is therefore an escalated need for discipline, time, intelligence, energy and communications and networking skills. It is very difficult and demanding for someone right out of school to start a successful business but it is entirely possible and if successful will produce great results. It is also true that the best lessons in life are learned in failure and so no matter what happens for young people you have lots of time and energy for recovery. Older people of course have credibility, along with many of the experience related advantages that age typically deliver. The difficulty in doing innovation later in life is a predisposition to standing true to what has experientialy taught you is the right or wrong way to do things. If you have responsibilities like a wife, home, payments, children or demanding lifestyle requirements you are severely impaired. You will also find it hard to get friends, family and others involved in the idea stage of your business because most are already consumed by their own needs and habits. Therefore you will be challenged to find allies and resources if you do not already possess them. Finally you will need to address the demands that starting something new will place on your time, energy and money so that you not sacrifice all of them for your adventure. After speaking to both sides of the issue my answer would be that no matter if one is young or old there are right and wrong ways to start. You need to have a brain trust and mentors at either age. You need a passion greater than money. You need family and friends whom you love deeply and who return love in the same way. All entrepreneurs need intelligence, discipline and an internal drive for action and change. Finally all who engage in startups will be favored by a faith in God. The reason is that in order to build valuable enterprises, strategies, trusting and faithful relationships and teams you can trust while staying committed and faithful to your personal values, family and friends you will need morals, ethics and a constant friend to help deal with the many hard quetions you will certainly face. Even though this is an opinion I hope that helps to engage people thinking about starting businesses to think of all that is required vs the perceived reward.
God Bless!