What does this mean? If you found your own company at 20, then 20 years later are you are 40 year old founder? If you are a serial entrepreneur, some companies

What does this mean? If you found your own company at 20, then 20 years later are you are 40 year old founder? If you are a serial entrepreneur, some companies will be started when you are young and others will be started when you are old. If you can do it earlier, why wait?