It depends on what you want to test.

When you want to test user acceptance and behaviour, you should of course test within your desired demographic. People from a different demographic might give you different results and mislead you about the strengths and weaknesses of your product.

But when you want to test for bugs, you need professional testers who thoroughly test all the edge-cases of your game, systematically looks for bugs, find out how to reproduce bugs they find and then write useful bug reports which contain all the information you need to fix them. This is not how a normal player plays and experiences your game. Feedback about the gameplay itself is just secondary, so it does not matter which demographic these testers fall under.

It depends on what you want to test.

When you want to test user acceptance and behaviour, you should of course test within your desired demographic. People from a different demographic might give you different results and mislead you about the strengths and weaknesses of your product.

But when you want to test for bugs, you need professional testers who thoroughly test all the edge-cases of your game, systematically looks for bugs, find out how to reproduce bugs they find and then write useful bug reports which contain all the information you need to fix them. This is not how a normal player plays and experiences your game. Feedback about the gameplay itself is of course welcome, but it's not what you expect from these testers. Their feedback is also not very useful, because they are testing the game and not playing it. That's a completely different perspective. So it does not matter which demographic these testers fall under.

It depends on what you want to test.

When you want to test user acceptance and behaviour, you should of course test within your desired demographic.

But when you want to test for bugs, you need professional testers who know how to thoroughly test all the edge-cases of your game, systematically look for possible bugs and file useful bug reports. A professional tester doesn't play the game like a normal player does, so it does not matter which demographic they fall under.

It depends on what you want to test.

When you want to test user acceptance and behaviour, you should of course test within your desired demographic. People from a different demographic might give you different results and mislead you about the strengths and weaknesses of your product.

But when you want to test for bugs, you need professional testers who thoroughly test all the edge-cases of your game, systematically looks for bugs, find out how to reproduce bugs they find and then write useful bug reports which contain all the information you need to fix them. This is not how a normal player plays and experiences your game. Feedback about the gameplay itself is just secondary, so it does not matter which demographic these testers fall under.