I don't recommend anyone flying this in the public area if they do not have the license. It can be very dangerous if it runs off the battery and falls down.
That should be common knowledge at some point in the future. But as of now its still pretty much the wild west here in malaysia when it comes to drones, even with laws in place.
hmm most likely is because the tiny drone you bought do not have much flight assistance built, probably only a basic IMU and maybe barometer. More expensive consumer drones might have more redundancy in place but will still crash into walls if the pilot doesnt know what they're doing.
The one hurdle in battery efficiency is the physical limit of energy storage/release potential in the chemicals inside the battery. Most drone batteries are made of Lithium Polymer and although they are the best batteries we have now in terms of cost and efficiency, there are still possible improvements to be made but the newer chemical pairs are much much more unstable unless we can come up with a way to contain the energy release.
There is an interesting (though nerdy) video on what is the absolutely theoretical limit on battery storage here
RE: 3 Basic Tips for a Drone Beginner - From a Professional