Boeing were first with the narrow fuselage dash 80. They put $16 million into R & D. Douglas then brought out the wider bodied DC-8. Boeing had to redesign the production model with a new wider fuselage - the 707-120.
The DC-8 was still winning the orders, so Boeing had to design a new bigger wing, stretch the fuselage, add fuel and put new engines on it (the JT-4A and RR Conways) for another new model - the 707-320 Intercontinental.
So by the time they finished they'd had to design and pay for 2 fuselage, 2 wings and integrate 3 engine types. The accountants hated them. The 707 only started to return a profit after several hundred had been delivered. The main financial success being the nearly 750 C/KC-135 bought by the USAF.
So a victory for the airlines and the customers. Definitely not the shareholders.