Some people get it and some are turned off by it. The reign of God would seem to be the very ground of reality. The grace of God, which we all need, only get’s its value because of Who is offering it. Grace that takes over is far superior to grace that merely forgives.
What makes the Kingdom of God the main thing, the big burner? Allegiance is indispensable to being sold out to the agenda of the King. The loyalty of the heart is the issue. If the focus of the Lord’s Prayer, ( “Our Father who art in Heaven, honored be Thy name, Thy Kingdom come, Thy will be done on earth as it is in Heaven”), is taken seriously, the Kingdom is supremely precious. If it is minimized and relegated to just one more thing in a variety of options, it is devalued.
When I personally discovered that the Kingdom of God is the Pearl of Great Price it changed my value system. It turned my life upside-down. The kingdom became a magnificent obsession. Once in a while I meet connoisseurs who also have sold everything to possess the ultimate prize. More often the reaction is a stifled yawn and a bored glazed look that tells me that the Kingdom gospel of Jesus is still undiscovered or unappreciated.
In order to buy the Pearl you have to “sell” everything else. That seems to be the sticking point.