No, 72 volts is way too fast for an ebike in my opinion. You risk a lot by going that fast. 48V is the max and is far safer.
This reply makes no sense. Slower machines are far less safe. I have 130,000 miles or so on my 2014 touring motorcycle. For that, I chose the BMW K1600, which is basically in a class by itself, because of it's speed capabilities (160hp, 134lbs torque, Zero to 60 in 2.7- without shifting out of first gear, a top speed of 150mph, and a design that lets it lean far enough to carve up the twisties at speeds other tour bike couldn't dream of.)
Absolutely no one goes out and tests all those capabilities on the road on a regular bases, as that would almost certainly result in death. However, there are frequently situations where those capabilities can and eventually will save your bacon! In the same emergency situation lesser bikes are left with choosing brakes or steering left or right, the K1600 adds the ability to hit the gas a d remove yourself from the situation... right now. Say you're on the 405 keeping up with traffic, with imbecile tailgating you, another car about to wiz past you in the passing lane to your Left, and a second imbecile drifts into your lane while staring at their phone... what do you do? Well, if I'm on your average big twin, it is already near it's limitations, so all I can do is pray. On the K1600 by contrast, simply give it some gas, and you'll leave the imbeciles like they were standing still. Speed is a valuable safety feature added to your options.
My current fastest ebike only hits about 34mph... but it's a damn sight safer than my e-fat bike, which only does 24mph... because it can get me out of more danger. I ride around Long Beach mostly, and use the kamoot app to track bike performance. On either bike, my average speed is almost invariably 16-17mph. Would I be safer on a bike that could accelerate twice as fast and hit even 50mph? You can safely bet your ass I would be, because it could get me out of more trouble.
I damned near learned this lesson the hard way, when I got caught in a storm on a 250cc Honda Helix scooter. Great ride, and "capable of highway speeds." Well that capability is wonderful, right up until you find yourself in a situation where the only way out is forward, and that requires more powdr than you have. Fortunately, I survived getting rubbed by an idiot in a car, but then found I hadn't ridden the bike again for like a month. I immediately put it up for sale, and never road it again, because I believed my dad when he told me that if you ever get afraid of your bike, sell it or you're going to kill yourself.
I signed up just to post this reply, because your advice is dangerously bad, but looks popular with others who know no better. Not everyone building an e-bike is a fearless teenager who will push it's limits every time they get on it. But they sure will be grateful for more speed if they ride long enough to need it to get out of trouble.
In short, your ability, knowledge and practice is what dictates your safety level, most of the time, but shit happens... and a more capable machine can only add to that safety if you ride responsibly.