If you have a goal in mind and you are focussed towards it, what may come, don’t give up. Like Siebel never gave up and did not let doctors cut his leg and instead found a solution; you can also find solutions. You have to be persistent, and talk to experts in that domain.
Before starting his own business, Siebel worked with Oracle and learnt a plethora of things. He learnt about sales, marketing, accounting, HR, etc. He also learn ‘trial and error’ and applied good practices in his own company.
After touching around $1 billion in sales at Oracle, Siebel wanted to build an application and he took his idea to Oracle CEO Larry Ellison, who said no. But, this did not discourage him. Since Siebel believed in the idea, he went ahead on his own. We have to decide for ourselves and make our own career decisions. Listen to your gut feeling and if you believe you’ve got what it takes, go for it