Guns: Every country that has had a gun ban strongly enforced has had a reduction in homicides. Every. Single. One.
But violent crime goes up though, as criminals feel they can commit crimes without a risk of meeting an armed owner for instance.
And the other poster is right: NASA never stifled spaceflight; they don't control aerospace worldwide, and there was nothing stopping anyone in other countries from getting into spaceflight. They sure didn't stop the Chinese and Russians from building spacecraft.
The environment outside the US was even worse. For example look at OTRAG. Aerospace is a highly politicized field, not to mention risky.
1. Self-driving cars are coming. That's pretty major.
2. Space-flight has been stifled for decades by NASA, no wonder we're finally seeing advances.
He who has but four and spends five has no need for a wallet.