dcumpian has pointed at the confusion here between the "strength of evidence" and the "absolute risk." The strength of evidence that firecrackers cause vision loss is very high. Someone hit in the eye by a firecracker as it is exploding very very probably suffered his subsequent immediate loss of vision in that eye as the result of the firecracker. Every year dozens of people lose an eye to a firecracker worldwide, but that is a very small risk when divided by the total population, or even the total population who have spent time within hearing distance of a firecracker. So firecrackers very clearly are capable of blinding, but your risk of actually being blinded by a firecracker is small.
You will quite probably reduce your risk of some cancers by avoiding "processed" meat. What your current personal risk for developing those cancers is depends on a lot of factors, and is not defined. A relative risk reduction can be misleading when confused with an absolute risk. If your chance of winning the lottery is ten million to one per ticket, and you buy two tickets, your chance of winning has doubled. That sounds like a large number, but your chance is still five million to one. A more instructive number you need to figure your benefit from quitting bacon is the number needed to treat (NNT). In the case of the lottery, how many people would have to buy a unique ticket number to be sure that one has a winner? It turns out that 9,999,999 people will be buying a losing ticket in order to be sure that one person has a winner. How many people who will never get the cancer in question if they keep eating bacon will have to quit to prevent one cancer? No one has collected the data and done the calculation that would answer that. So the question is...do you feel lucky?