Because it costs so much electricity, several countries have imposed restriction on mining activity?
no you are mistaken because of a lot of FUD in the media. there were no several countries ever! what happened was that a tiny place in New York State started planning for some restrictions on usage of electricity and that news was exaggerated in less than a day into a big FUD.
you don't have to worry about miners they are making their profit (with or without your worrying!) thanks to the way bitcoin is designed (difficulty and all that) and also not to mention the potential of growth that bitcoin has.
I've heard about that. Exaggerated indeed. Mining would always ptofitable as long as you do a right calculation , a great skill to see an opportunity like when you've mined Bitcoin usually miner sell it all due the cost that need to be cover up soon to restart the business and instead you sell it all , hold some whenever you see a great potential ahead.
Normal thing indeed when you sell you mined coin all at once , think about how if you put it as an investment for longer time , your electricity cost would get covered sooner or later , that is why you better start mining with extra money in your pocket.