Wingsuit pilot & programmer here. The reason Wingsuit BASE Jumpers keep dying is that you shouldn't jump your wingsuit off a @#$%ing mountain. Please stick to the planes and the helicopters that you're used to.
It's an addictive feeling, and it can trick you, because you know it's dangerous but you're always come out of it fine, great even, until you don't.
That was for motorcycles where accidents are survivable and things are much more in your control.
For low wingsuit flying those last two points are both questionable.
[Base Wingsuiting] is safer than regular base jumping provided
you don't try to strafe tree and hilltops and cliffsides
A wingsuit can give you freer air for deployment, which increases the margin for error, but wingsuit BASE seems to be aimed at proximity flying.
Can any pilot practicing BASE Jumping leap off a cliff or do you somehow train for this?
The general training arc would be to learn wingsuiting from an aircraft (like a regular skydive), and build up hours/experience flying a wingsuit in clear air (and deploying a parachute several thousand feet above the ground), before going into wingsuit base jumping (and build up experience there before going into prox).
There's some more detail in this Quora answer: https://www.quora.com/What-does-it-take-to-become-a-wingsuit...
What struck me about the profiled jumpers was their calm, sane demeanor -- not the showboat thrillseekers I expected.
BUT, most seemed unsatisfied by the experience when minimizing risk. To me, being 100 or more feet from terrain would be the experience of a lifetime. But many leaders in the sport keep pushing the envelope to a fatal degree (and in each example it was terrain, not equipment failure or weather).
Antennae
Span
Earth
You can pilot a wingsuit from a plane or much higher, but most of the people that die wingsuit flying are proximity flying - which has way smaller margin for error and higher mortality rate.
Do you just jump and then use a parachute when you get low enough?
A few people have landed with their wingsuits, but that's pretty rare. Look up Gary Connery or Jeb Corliss for example.
You are still going pretty fast, you need ideal terrain (angle, water or boxes), and a hundred things have to go perfectly fine. It's a pretty insane feast.
Then pull your chute whenever.
Here's an example: https://www.youtube.com/watch?v=K2VIbrVVQRw