If you want to be a better hacker. Than you should learn how to hack hardware. Low level hacking is the way you should go with. You must learn hardware level programming like machine language.

There are two types of hacker:

1: Operating System Level (High level) hacker: This type of hackers are easily can be prevented. They can only hack one type of Operating system (example: Windows only, Linux only or MacOS only...). Also their hacks are not persistent/permanent. A format or a anti-virus scan can get rid of these type of hacks.

2: Hardware Level (Low level) hacker: This type of hackers are persistent and permanent on the target system. The hackers that targeting me since 10 years ago are this type of hackers. No body(polices or other legal authorities) believes me. This type of hack is not detected by most(%99.9) of IT experts. If you hacked by one of this type hackers, then it's most likely you never will be detected. And another advantage of this type of hack is you can hack not only the Smart devices but also devices like air conditionings or keyboard and mouses.

What you can do If you choose to be a low level hacker:

You can hack any router on the world with a hardware level zero day vulnerability. Then you can send a fake update to the device's OS which connected to the router/modem. Or you can send a fake update for any software thats installed in the target devices OS.

You can also hack devices like Ethernet chips or voice/sound chip on the motherboard. No one looks inside of these chips for a malicious code.

You will be like a god. You can over-voltage a component on the circuit. This way you can burn the device and it can cause a fire like Israel's Government Hack Group did in Iran (They exploded transceiver in Iran with a hack). Possibilities are almost unlimited.