While a small win on the lottery could be kept quiet, there is no way a win of this size could be kept quiet.
You only have to tell one other person and news would get out.
And do you think if you told your sister or brother or mother or father that they would not tell anyone....it would spread like wildfire.
I actually feel sorry for people who win this much money because of all the problems it would bring (worry of kidnap of children, burglers, attitude of relative and friends etc - if you dont give them money you are a skinflint, if you do give them money you are showing off - you cant win).
Personally I would ban lottery wins of this size. It is obscene a person can win this much money.
A local charity near me that looks after my disabled son may have to close because they have lost £20,000 of their funding, then one person wins 148 million on the lottery - disgusting.