Hi stuuke,
Yes there are many people that sleep on their mattress for longer than 10 years but anything over 10 years is what I call “bonus time”.
There is also no way to specifically quantify how long any mattress will last for a specific person or predict exactly when they will decide to replace it because it is no longer suitable or comfortable for them (because this is the only real measure of durability or the useful life of a mattress that really matters) and because there are too many unknowns and variables involved that are unique to each person … if a mattress is well inside a suitable comfort/support range and isn’t close to the edge of being too soft when it is new (see post #2 here) and you have confirmed that it meets the minimum quality/durability specs that are suggested in the guidelines here then it would be reasonable to expect a useful lifetime in the range of 7 - 10 years and with higher quality and more durable materials like latex or higher density memory foam or polyfoam (in the comfort layers especially) it would likely be in the higher end of the range or even longer and the chances that you would have additional “bonus time” would be higher as well.
Phoenix