Alright let's think *stick tongue out and look up*
Obvious suspects.
Hitler: Guy who wanted to regain Germany's rightful rule and glory, in the processing doing some cleaning.
Stalin: Guy who loved to sit on Gremlin's throne and as insurance paid for it by millions of slain bodies.
Dahmer: Do I even need to type?
That's enough. Let's go with those three. The heart Hitler had doing that cleaning, He'll have in heaven, so will we make him our official ethnic janitor? Stalin will have the same heart too, I wouldn't want to sell anything to him. Dahmer... probably would not want to hang out with him either. 3 men that society today call evil to the core. How can evil, like that, exist in Paradise, while it still remaining in the state of Paradise? We just got into 3 souls, what about the remaining hundreds of billions of souls, a vast majority of them without a new heart? Those who raped, those who molested kids, those who stole, those who killed, those who killed to steal, those who killed to steal a rape on a kid, and so on and so on. We got liars who can't be trusted, we got greedy and envious people who will just take advantage of you. We got sailor mouths who only want to look after their self. How can these exist in a Heaven, and it still be a Heaven?
You know why Paradise is a Paradise? Because the heart of every soul in that Paradise will be walking perfectly in one thing: Loving your neighbor as yourself. Heck, they'll love their neighbor even more than themselves. That's actually the Law and the Prophets according to the Lord, that is really the core of the Will of God. That is the expectation, requirement, standard, whatever you wanna call it to get in there. Notice though, they don't just love from their deeds and words, but from their hearts. No evil against another can be conceived in them.
That is the image His own is being conformed to so that Heaven will still be a Heaven, New Earth will be an Earth fitting for the eternal presence of the God of Majesty, and Paradise will be as sweet as it sounds. Not everyone wants that, though. You know why? That love requires sacrifices that rarely anyone, not even Christians, are willing to make. If you don't want that, you don't want paradise.
Of course there is also the God that will be there, who's presence will be as real as you can get every single time for everyone there. They'll be a lot of love, God to His people, His people to God, His people to each other, angels to rocks to plants to people to you get my point. So if you don't want God, you don't want paradise.
So where else can someone go when they don't want that heart, nor do they want God? The only place that is described to being from the presence of the Lord, and from the glory of His power.
Why Hell? Because people wanna go there Mr. Thinker.