By not voting you are giving the majority of your vote to the winner.
What maths is this???
Consider a population of 10 people, to simplify the problem.
4 vote for party A. 2 vote for party B. 2 vote for party C.
2 abstain, neither A, B, or C represent their interests.
By your logic A now gets those 2 votes to win an overwhelming victory of 6 votes.
But this is not true. A still has less than 50%, and only double what B and C got.
So sadly your maths is badly wrong and does not show that not voting is in any way giving your vote to the winner...
And votes cannot be split so you are also "not giving the majority of your vote" to anyone. A non voter in the above scenario makes a valid point: while 20% of the population are interested in parties B and C, there remains 20% who are voiceless and unrepresented.