Startups are about disruption.

Disruption, by definition, means that legacy players (otherwise known as incumbents) are having their world changed/disrupted in some way.

When dealing with incumbents...

You want to: address their concerns and overcome them with better products, user experiences, and business models. Along the way, focus on those who get it and ignore the rest. They'll either jump onboard later or die.

You do NOT want to: Compromise your vision and work around their fears. You don't want to waste too much time trying to convince those who resist change.

Better: Whenever possible, go directly to the demand side (end-customers) and control the transaction end-to-end. Cut incumbents out or - worst case - come to them with deals/$ (not hat-in-hand asking them to change their business with a clever new product).