I don't see a problem with the break chance as the developer has it. There is a 97% chance of an item not breaking. Across 7 equipped items it comes out to an 80% chance of not breaking any items (20% chance of something breaking). If you have three heroes, all with seven items at 3%, you have close to a 50/50 shot of one item breaking. You have to keep in mind that even though 3% is the percentage for a single break, you have 21 RNG rolled in a combined event.
If you want to better your odds, invest is some mythical or legendary gear.
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Thank you for your explanation!