The short story of Odysseus's revenge on the suitors boils down to a few details: he didn't return from the Trojan War in a timely manner, so his community assumed he was dead. Suitors came to his house to woo his wife, Penelope, but she will not choose one until she has proof that Odysseus is really gone. The suitors, however, will not leave until she picks a new husband from their ranks. They proceed to take advantage of the resources of Odysseus's home for years, eating his food, drinking his wine, slaughtering his animals, and so on. Worse, they won't even share with Odysseus when he is disguised as a beggar! They've taken advantage of his home's hospitality and exploited it, and they've disrespected his wife and son.
In modern life, we might find an equivalent if a woman's husband went away on a long trip and never returned; let's say that his plane crashed into the ocean but his body was never recovered. Now, the community insists that she hold a memorial service so that people can mourn him, and even though she doesn't believe he is dead, she feels obligated to do so because it is socially appropriate. After the memorial service, everyone comes back to her house for lunch and then, suddenly, all her husband's old friends refuse to leave until she chooses one of them as her new husband. They set up camp in her home, eating up everything in the pantry, raiding the wine rack, driving his Lexus, and flirting with his daughters. Finally, one day, after several years, the man returns. He is exhausted and all he wants to do is see his wife and kids and relax in his home for the first time in a very long time. Instead, he finds it infested with smarmy jerks who are getting fresh with his wife and using all his stuff. He'd probably very likely seek revenge too, although he might simply choose to sue them for damages. Obviously, litigation is not the way ancient Greek heroes resolved their conflicts, and so Odysseus takes revenge in the best way available to him: by killing them all in cold blood.