While it's true that those in their 30s or older can be closed to new idea, that's not because they're "old", it's because they're people and some people are closed-minded.
I feel social pressure plays a big part. Even the so-called open-minded 20 year olds will make fun of people in their 30s and 40s who still try to live an "unsettled" lifestyle. To accept wild and crazy ideas in your 20s just means you still have some growing up to do. To do the same later in life shows an abandonment of your responsibilities, which is frowned upon by society – in North America, at least.
I feel social pressure plays a big part. Even the so-called open-minded 20 year olds will make fun of people in their 30s and 40s who still try to live an "unsettled" lifestyle. To accept wild and crazy ideas in your 20s just means you still have some growing up to do. To do the same later in life shows an abandonment of your responsibilities, which is frowned upon by society – in North America, at least.