Thanks to this tip:
Instead of the above, you can also try one of the extensions, which allows you backup and sync your bookmarks across computers and browsers, e.g. the "Xmarks Bookmark Sync" - to install this extension, you must first install one of the following extensions: "Extension source viewer", or "Download Chrome Extension". For more details, please have a look here.
I'm able to use Opera as my main browser. Because without a way to synchronize my bookmarks or at least easily import and manage them from my other browsers, even though liking Opera it was a no go for me.
And I know this is a Windows forum, but I use this tip on my Mac and it worked fine too.