There is no thumb rule on this one - for some doing it on their own works better and for others having a professional is best. There is no 'one size fits all' cap on this one.
I believe you would not have made the mistakes that you did had you taken a professional. So I agree with you.
Just like one can't judge an entire country based on one person, similarly there is no way to judge what works better for which person. Ideally the person show know it best what works better for them. There are successful cases either ways, and there are unsuccessful cases both ways too!