Will a worshiper be rewarded if he prays a supererogatory prayer as a precaution, following the Holy Quran, in light of some scholars' opinion that intentionally missed prayers are not obligatory to make up and are not accepted?

The difference of opinion on this matter is well-known. The preponderant view is that intentionally missed prayers should be made up as a precaution for one's religion and to absolve oneself. Whoever makes up these prayers, doing so as a precaution and in accordance with the view of the majority, will be rewarded for their prayer, for Allah does not let the reward of those who do good go to waste. Even if the truth with Allah is that making them up is not obligatory, one will still not be deprived of the reward.