The question, as stated, is an offshoot of Pascal's Wager. More specifically, the question is assuming that the assessed risk is legitimate.
It would be like asking, "What if you are wrong about there not being a monster in your closet?".
Well, then I would get gobbled up by the monster in my closet.
Admitting that the consequences to being wrong would be bad does not mean I should build an altar in front of my closet door, sacrifice animals to appease the monster, pay 10% of my income to have professional anti-closet-monster priests bless my room, and end all investigation into determining whether there in fact is a monster in my closet.
Instead, I will investigate the matter, and if no evidence supports the claim, not believe it. It would be silly to take steps to mitigate a supposed danger that, for all intents and purposes, is not demonstrably real. We do have better things to worry about.
People in our society do not fortify their houses, or take defensive actions, against Tyrannosaurus Rexes running around, because no evidence exists that indicates that this is a problem. And yet, we have far more evidence that Tyrannosaurus Rexes existed than an afterlife, let alone a bad afterlife.
Additionally, those who ask this question are usually ignoring other possibilities to be wrong about. For instance, frequently Christians will ask the question in regards about their god, without realizing that Muslims would be asking the same thing about the Muslim god.
Instead of a vast multi-connected unsolvable network of every person asking every other person "What if you're wrong?", the important, relevant question should be asked.
"Do any of you have any evidence for your claims?"
- Isn't "believing that God doesn't exist" the same thing as "not believing in God"?
- Do you only believe in what you can see, touch, feel, etc?
- Why do you ignore all the evidence around you for a god?
- Where does morality come from, if not God?
- Why do atheists support gays so much?
- Do atheists believe in nothing?
- Are you afraid of going to hell?
- If it wasn't God, who created the universe?
- Why are you so closed minded?
- What is the point of living without an afterlife or god?
- What if you are wrong?
- Can you prove that God doesn't exist?
- Will you admit that there is a possibility of a god?
- Do atheists have faith?
- Where does the meaning, and purpose of life come from?
- If there is no god, how do you explain _______?
- Why do atheists have faith in science?
- Are atheists empty, unhappy people?
- What bad experience made you hate god?
- Where to do you go when you die?
- Do you believe all this came about by random chance or by accident?
- What would it take to prove to you that a god exists?
- Why don't you just sit down and shut up, and let others have their beliefs?
- Why are atheists so angry?
- Aren't you just rebelling against God because you want to sin?
- Isn't it arrogant to say that science has all the answers?
- Wouldn't it be safer to just believe than risk going to hell?
- What is faith?
- Have you tried to believe in God?
- Why did you choose to be an atheist?
- Doesn't you being so against God prove he exists?
- Is atheism a religion?
- Where do you think rights come from, if not God?
- Do atheists want to take religious freedom from Christians?
- What is in it for me to be an atheist?
- Don't atheists believe there is no god?
- How do you know you are right?
- Do you believe in a soul or spirit?
- If you don't worship God, do you worship yourselves?
- What is an agnostic?
- Don't you have to be skeptical about skepticism?
- What is the difference between an agnostic and an atheist?
- What do you base your beliefs from?
- Don't you know that you're just supposed to have faith?
- What is an atheist?
- Why do you ignore god?