"You've got everything in the world to be thankful for; but the more you get the more you kick" implies that: Consumers in the 1920s were very careful with their purchases
Consumers in the 1920s were very careful with their purchases

Consumers in the 1920s were greedy and always wanted more
Consumers in the 1920s were greedy and always wanted more

Consumers in the 1920s were not interested in new products
Consumers in the 1920s were not interested in new products

Consumers in the 1920s were interested in new products but did not overspend