I honestly think that a lot of them come from a position where they were either A) "top dog" or B) sequestered mentally in some way so their ideas were never challenged.
Me, I grew up the oldest of three by four and eight years, and was always the oldest kid on the block by some years with no one to hang out with really but parents. When I left high school and started an office job, I was the youngest in the office by at least 5 years, so again, I was hanging out pretty much all the time with older, more experienced people. I learned quickly how easy it is for your ideas to get stomped on. I also unfortunately (or fortunately) developed at taste for expensive booze because older, more experienced coworkers are way past the college cheapo days.
Me, I grew up the oldest of three by four and eight years, and was always the oldest kid on the block by some years with no one to hang out with really but parents. When I left high school and started an office job, I was the youngest in the office by at least 5 years, so again, I was hanging out pretty much all the time with older, more experienced people. I learned quickly how easy it is for your ideas to get stomped on. I also unfortunately (or fortunately) developed at taste for expensive booze because older, more experienced coworkers are way past the college cheapo days.