BrodyFosse123 said: "...That’s why she was offered HELLO, DOLLY! though everyone was aware she was way too young for the role. Career wise it made sense."
From 20th Century Fox's point of view, Streisand would put butts in seats.More than Channing, or any of the women that followed her in the role on stage. It made marketing sense.
Streisand, on the other hand didn't want to do it. It was 1967 and every year that went by, Dolly seemed more a relic of the past and not relevant to anything going on in the real world.
Her agent, Marty Erlichman (who is still her agent!) wanted to use the offer from Fox to bump up Barbra's asking price in Hollywood. Ray Stark had low-balled her on Funny Girl because he knew she couldn't turn it down. Erlichman sent Fox a counter offer of $1 million for Streisand to do the picture. The only other actress to have been paid that much at the time was Elizabeth Taylor on Cleopatra - and that was only because the movie went so over-schedule and they had to pay her penalty fees. Marty's thought was that Fox would reject the offer, but then word on the street would be that was what you had to come up with if you wanted to hire Barbra Streisand.
To their great surprise, Fox took the offer. Why? A.) they wanted Barbra, and B.) they knew the $1 million salary would generate publicity for the movie. It would almost be worth it just for the free press it would generate.
Which left Streisand stuck with the movie after they essentially called her bluff. She couldn't back out or the whole future salary gambit would be all for nothing. This is the way the sausage gets made.