Yes, what if someone controls 50% of the mining ?
Now some miners have ~10% I think.
You can see a rough picture of the situation here
https://blockchain.info/poolsPool know that having over 50% constitutes a risk for the community.
They don't want to devalue the coin themselves, as it is their revenue. Going above 50% is discouraged.
So that means mining for newcomers is not advise in bitcoin because of the institution who control 50 % of power .
kindly advise . thxs