Why Does God Give Grace to Some and Not Others?

ESV Romans 11:1 I ask, then, has God rejected his people? By no means! For I myself am an Israelite, a descendant of Abraham, a member of the tribe of Benjamin.
2 God has not rejected his people whom he foreknew. Do you not know what the Scripture says of Elijah, how he appeals to God against Israel?
3 “Lord, they have killed your prophets, they have demolished your altars, and I alone am left, and they seek my life.”
4 But what is God’s reply to him? “I have kept for myself seven thousand men who have not bowed the knee to Baal.”
5 So too at the present time there is a remnant, chosen by grace.
6 But if it is by grace, it is no longer on the basis of works; otherwise grace would no longer be grace.
7 What then? Israel failed to obtain what it was seeking. The elect obtained it, but the rest were hardened,
8 as it is written, “God gave them a spirit of stupor, eyes that would not see and ears that would not hear, down to this very day.”
9 And David says, “Let their table become a snare and a trap, a stumbling block and a retribution for them;
10 let their eyes be darkened so that they cannot see, and bend their backs forever.”