Not much.
God sent the flood when few were righteous on earth. Ge 6:
5 The LORD saw that the wickedness of man was great upon the earth, and that every inclination of the thoughts of his heart was altogether evil all the time. 6 And the LORD regretted that He had made man on the earth, and He was grieved in His heart. 7a So the LORD said, “I will blot out man, whom I have created, from the face of the earth”
God sent judgment against widespread wickedness. He also sent Noah to warn his contemporaries. 2 Peter 2:
5 if he did not spare the ancient world when he brought the flood on its ungodly people, but protected Noah, a preacher of righteousness, and seven others;
Next, God destroyed Sodom and Gomorrah because Genesis 18:
20 The outcry against Sodom and Gomorrah is so great and their sin so grievous.
God could not find 10 righteous people in the cities (v 32).
Lot was a righteous example for them. 2Pe 2:
7 if he rescued righteous Lot, greatly distressed by the sensual conduct of the wicked 8 (for as that righteous man lived among them day after day, he was tormenting his righteous soul over their lawless deeds that he saw and heard).
Again, people were destroyed wholesale when wickedness was great and righteous people were rare.
Concerning the 2nd coming, Jesus spoke in Lu 18:
7 "Will not God bring about justice for His elect who cry out to Him day and night? Will He continue to defer their help? 8 I tell you, He will promptly carry out justice on their behalf. Nevertheless, when the Son of Man comes, will He find faith on earth?”
Perhaps not much.
Similarly, Paul in 2 Timothy 4:
1 I charge you in the presence of God and of Christ Jesus, who is to judge the living and the dead, and by his appearing and his kingdom:
Jesus will come again to judge people.
2 preach the word; be ready in season and out of season; reprove, rebuke, and exhort, with complete patience and teaching.
There will be righteous people who warn the wicked, but they will not listen to righteous teachings.
3 For the time is coming when people will not endure sound teaching, but having itching ears they will accumulate for themselves teachers to suit their own passions, 4 and will turn away from listening to the truth and wander off into myths.
Just like in Noah's day, there will be great wickedness on earth. A few righteous people will warn them, but they will not listen. Then Jesus will come to destroy and judge.
