The phrase "bigger barns" means accumulating more possessions or wealth than what is needed or necessary. It suggests a desire to acquire more and more, even if it surpasses our actual requirements. Full definition
Then maybe someone could hand paint a great big barn quilt design right onto them. (theletteredcottage.net)
Which brings us to Jesus» story about the man who stored up grain for many seasons in his barns, with such a surplus that he thought of building bigger barns. (religion-online.org)
Maybe they like pushing big barn doors open into oncoming traffic. (autoweek.com)