Do leaderboards stop the desire for social sharing?

Been thinking about adding a universal leaderboard to my app, but like everybody else I'd also like the app to have a chance of going viral.

The thing is, for an app to go viral users need to share their scores/screenshots/etc across social media, but would users actually do that if a leaderboard was in place? They'd be more focussed on their place on the leaderboard as the people they're competing against are already on there - and this then satisfies their desire for a Look at my highscore! Bet you can't beat this... type of social sharing, as they don't care about the wider world, just the users already on the leaderboard. And this leads for a more insular experience and less of a desire to share.

Obviously you can have both leaderboard and social share buttons - and while I think having a leaderboard does bring people back to have one more go and slowly work their way up, I also think leaderboards can work against social sharing and the desire to brag.

What's everyone's thoughts on this - leaderboard or not?

Leaderboards are brilliant for increasing user engagement, and adding to the longevity of a game.

Don't think of it as something that is in conflict with Social Sharing, but rather either complimenting, or an entirely separate element.

You can boost the social sharing side of your game with incentives such as free in-game currency or lives etc for each share. I have 3 buttons that each give free coins when clicked; Rate Game, Facebook post, Twitter Post. You'll have to record to memory whether they have clicked them or not. Some people will abuse this, but it's more than worth it!