Right now we don't really use bitcoin and we just store it. So from this point of view it could be kind of a waste of electricity. Obviously that we can't forget the potencial for bitcoin to be used as a currency as well, so if we ever get there, then it's energy consumption wouldn't look that bad anymore.
No, this is wrong. Bitcoin has been using most or all of it's transaction capacity for several years now. The recent blocksize increase hasn't yet reached the new saturation point, but it will eventually get there.
Additionally, you're amply demonstrating that you don't know why Bitcoin is mined at all. Even if there were little to no transactions (as you apparently believe), Bitcoin's proof of work does perform a beneficial task:
cumulative protection of Bitcoin's censorship resistance (every new block in the blockchain strengthens it's immutability further)
I wasn't saying there were no transactions. I was saying that right now, the only real use for BTC is to be uses as a store of value. Even gold, that is also a store of value asset for excellence, has many other applications (like electronics, medical, dental and is even used in aerospace industry). The energy cost to mine gold, and to keep it safe, is probably bigger than the energy to mine bitcoin. But if we analyze all the practical uses gold has, then we will probably accept that it has a reasonable cost, to all the benefits it provides.
What I was saying about bitcoin, is that if BTC only works as an asset, and has no other practical uses, then one could argue, that it's costing much more than what its actually contributing to society. Like you said this is hard to analyze, and I'm not saying I agree with it. I actually think that bitcoin mining has a fair cost to benefits BTC brings to our economy.
What I was also saying, is that this last "argument", used by many, might fall completely if BTC manages to solve it's scalability problems (probably with the LN), and can present itself as a form of payment widely accepted by merchants.
As for how mining works, I think I have a basic knowledge about it. I know that blocks act as ledgers, and the transactions are stored there. A block can only be "added" to the blockchain, once it has been "validated". In order for that to happen, miners need to confirm transactions and put them in those blocks, and when everything is done, a hash is created and is also stored in the block. That hash itself is used to create the hash of the next block, so everything is "connected" and it's impossible to forge fake blocks because "everyone" would know that and reject them.
Miners "compete" with each other during this process, and who ever finishes it first, gets the reward.
Now, like I said I have basic knowledge about this, and as far as I know, this process of creating a hash would be way to easy, and all coins would be mined in minutes. This is where "proof of work" comes into place. A hash needs to look a certain way, and miners can change some part of data on the block, in order to keep trying to generate a hash that is valid.
Basically miners keep the network secure. I probably said a lot of bad things here. Like I said this is just my basic notion of mining, but even if any of this is wrong, I know that miners are crucial to keep the network safe.