God banished Satan from heaven, casting him down to earth. Satan thereupon tempted Eve to eat the forbidden fruit, speaking to her through the serpent. Satan then argued to God, "Condemn me, condemn them."
Satan is still on earth today, alive and well, "seeking whom he may devour" (1Peter 5:8).
See also Job 1:6-22.
Satan is STILL... in the Heavenly dimension. You're being silly with a primitive belief that Satan lives in the earth literally. Satan is a HEAVENLY CREATED BEING, not a flesh person, though you are treating Satan as such.
For Satan to no longer be allowed in HEAVEN, as the Rev.12:8 Scripture says as written, it means he will show up on earth like how the angels in The Bible have appeared to flesh-born men. Haven't you ever read in God's Word about those angels that appeared on earth with the image of men?
As of right now, Satan is able to "devour" FROM his Heavenly abode. And he is still today allowed in HEAVEN to approach God's Throne to accuse us before God, like he did per the Book of Job.
Where you are pulling from is a tradition of men that wrongly interprets what Jesus said to His disciples just before His being delivered up...
John 12:31
31 Now is the judgment of this world: now shall the prince of this world be cast out.
KJV
Men's tradition says that at Jesus' cross the devil was cast out of Heaven to the earth. That's not the timing Lord Jesus was referring to though. Lord Jesus was pointing to the day of His future coming when the 'actual' "judgment of this world" will occur, and Satan will be cast into his pit prison in chains, per Revelation 20. Now if you believe this world has already been judged then it would mean you wrongly believe God's Great White Throne Judgment has already happened; it hasn't, and won't happen until after Christ's future coming and "thousand years" reign of Rev.20.
John 14:30
30 Hereafter I will not talk much with you: for the prince of this world cometh, and hath nothing in Me.
KJV
Then later, Jesus tells His disciples that "Hereafter...", meaning after His being delivered up to be crucified, He will not speak with His disciples much. And then He warns that Satan is coming to this world. And that is the future casting out of Revelation 12:7 forward for the END of this world when Satan will appear in Jerusalem to mimic Christ Jesus, working great signs and wonders to deceive the whole world. That is the casting out of Heaven that Lord Jesus was pointing to.
Eph 6:12
12 For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.
KJV
Paul was referring to the Heavenly dimension when he said the above. When the event of Revelation 12:7 forward happens, those powers not of flesh and blood will literally come to this earth, in plain sight. Per God's parable in Ezekiel 28 about Satan, he is to be destroyed right here on earth, in plain sight, a fire happening within him, like a spontaneous combustion event. He has to come to this earth literally in plain sight for that to be fulfilled...
Ezek 28:17-19
17 Thine heart was lifted up because of thy beauty, thou hast corrupted thy wisdom by reason of thy brightness: I will cast thee to the ground, I will lay thee before kings, that they may behold thee.
18 Thou hast defiled thy sanctuaries by the multitude of thine iniquities, by the iniquity of thy traffick; therefore will I bring forth a fire from the midst of thee, it shall devour thee, and I will bring thee to ashes upon the earth in the sight of all them that behold thee.
19 All they that know thee among the people shall be astonished at thee: thou shalt be a terror, and never shalt thou be any more.
KJV