It's an efficient store of value. Here is a dilemma - you have 10 million dollars. You need somewhere to park your money. Do you follow the Chinese businessman pattern and buy real estate in Toronto? That seems complicated - picking a property, being subject to the real estate market, etc. Often these houses sit empty, since you are on the topic of wasted resources.
Do you buy gold? Gold is as useless as Bitcoin, in terms of intrinsic value, your special snowflake "industrial applications" of coating McLaren F1 engines as a heatshield and superconductivity aside.
Buy stocks? How do you pick them? A financial advisor certainly won't do it properly for you. And the fed is pumping out USD.
Of course USD is going to deflate.
So, Bitcoin suddenly doesn't seem so useless.
"is the huge energy waste"
Gold takes a lot to store, secure, and transport. BTC replaces that with mining.
"The second one is that it makes illegal activities easier, and at a larger scale. It's quite common right now for companies to be coerced pay millions of dollars to anonymous criminals, all enabled with cryptocurrencies."
Every single transaction is on the chain. At this point they are worried that Monero is insecure. There are even conspiracy theorists saying that "the man" wants blockchain currencies as the norm due to the "nowhere to hide" policy.
And yes, you can create a wallet on some hotspot, and it is "anon". But let's be honest.
"Unless equally sized positive effects would emerge"
It's a secure place to park cash that doesn't deflate by nature.
edit: If you downvote, try to explain what you disagree with.