The power markets are quite segmented and colloquial - regional FERC RTO/ISO's do allow approved and vetted 'marketers' to provide liquidity in the real time and next day LMP markets (INCs, DECs, UTCs, that type of thing) which is essentially an OTC bilaterally cleared market run by the regional ISO. Takes DEEP pockets and membership is required. There is also a financially cleared Swaps market run by Nymex (Clearport) and ICE (London Clearing House). Also takes DEEP pockets. This is a seriously adult swim.
Not that I’m personally aware of - again, very deep pockets. This is like choosing to snorkel off the Farallon Islands during seal calving season. I am not aware of a more volatile market - including cryptocurrencies. I have literally seen daily vol at 1,000% during July and August. I saw a prominent German IB desk lose $25M in a single day Trading the ERCOT real time market - lots of stories like that.
A good friend of mine trades these, lots of interesting stuff to do apparently - especially if you have a fair understanding of the capacity for various players.
Basically the industry vets drain money from hedgefund noobs who don't understand the ins and outs but are attracted by the volatility. "Look, a bright shiny object!"