He is insecure because Ukraine is giving him such a tough time and he knows that Europe would absolutely kick his teeth in in a fight. As usual all he can do is yell nukes.

Putin had a very insecure childhood, and he learned from a rat, that lashing out violently could scare off an attacker way bigger than yourself.
Unless he is extremely delusional, he is probably very worried ATM, because FSB (KGB) seems to be removing some of his strongest supporters.
So Putin may be nearing the end of the line, and he knows it. So he is lashing out because he is scared, while at the same time trying to appear calm and in control.
Putin is becoming more and more isolated. He is losing popular support, because the population is beginning to feel the costs of the war. He is also losing support from the elite, because the failure of Russia to defend their oil industry, has sown doubt that he can protect Kremlin and Moscow. And they too probably see their positions as being in danger. Finally even the FSB seems to be contemplating a shift in power, and they have moved way more boldly and apparently independent from Putin in later months.

So it seems Putin has enemies all around him, and he is probably paranoid already as a result of his childhood. So even if the threats are only superficial, he is most likely afraid. And many Russians don't believe he can win the war anymore, and even if they believe he can, many don't think it's worth it, because they will take over only ruins, and it will be expensive to rebuild, when the Russian infrastructure is already failing as it is.

So if you think it's exciting to live dangerously, I'm sure Putin has a lot of excitement right now.
Putin has been lucky so far that Moscow is having a mild winter, when the winter gets cold, many Russians will freeze, and many will run out of money, and things may heat up in other ways.

This man-child has an army and he is using it right now.