My son, the dare devil

We have a pretty steep narrow driveway as part of our house. It's not horribly steep, but still has quite a slope on it. There have been many a times we can't get our cars out of the driveway without shoveling the snow off of it in the wintertime. My boys love to ride their bikes and scooters. Yesterday was actually pretty warm so they spent part of the afternoon outside riding.
I went to check on the boys yesterday and my two year old took his bike (a 3-wheeler, like a big wheel) to the VERY top of my steep driveway, lifted up his feet, and went barreling down as fast as he could with a big grin on his face. I was scared for him because at the bottom of the driveway there is grass, but there's also plum tree right in the center as the driveway ends. Thankfully, he knows how to steer and steered the bike so he went right past the plum tree and about 10 feet onto the grass. He loved it and thought it was great while it scared me half to death. I tried to compromise with him and get him to go only partway up the driveway so as to avoid a heart attack on my end, but whenever he could he started at the top of the driveway.