I repeat the concept of him killing her elsewhere and dragging her down into the basement does not make any sense. If he had killed her elsewhere and wanted to kill himself there would have been ample locations with pipes railings Etc that he would have been more likely to hang himself from. The concept of him dragging her all the way down to the basement where it is only a lap pool is ludicrous. People commit suicide in a location that they are very comfortable with so the idea that he would go to tremendous lengths to drag his wife into this random seemingly random location is just not consistent with that line of thinking. That line of thinking would have had him hanging himself nearby to where he had killed her only thinking that he could not live with himself. Why drag her all the way down to the basement lap pool and then quite literally string her up next to him? This was a scene staged to make them look bad and staged to be shocking which is the signature of some kind of hit. As I have repeated we cannot even really speculate on the number of motives there would be for a murder of a billionaire. This is trickier than a usual case because even some of the smaller issues to a billionaire would involve millions of dollars. Just think logically about this idea that he killed her elsewhere but then dragged her down stairs into the basement string her up next to the lap pool and then hanged himself by the lap pool. It does not make any sense if what you are saying is that he wanted to die nearby his wife. I saw the photos of the house and there would have been about a dozen locations that he would have went to before he would have dragged his wife's body downstairs to be by the lap pool. This was a scene staged for shock value.
Theory :
Perhaps he was about to finalize a new will that cut someone out and they were aware of being cut out of the will. This would explain why BOTH husband and wife were killed. I think we should really be thinking if you discount the concept of murder-suicide, then why were BOTH of them killed. If you conclude murder, it is a critical detail that someone went to the lengths of not just killing Barry but killing both of them.
This is one of a million theories that should be considered before everyone is just like "OK murder-suicide...makes sense.", because no, it really doesn't. People have read his comments about there being no God and life having no meaning but the second part of that quote relates to living for the sake of achievement and this man was continuing to achieve in his life. Murder-suicide is about as likely as the other million of motives there are at this point. They are all equally unlikely due to the strange nature of the scene, so they are all one in a million... but only one of them is the real truth. The elites who really know what Barry was "into" might close ranks on the police and we may never know what the true motive was for their demise.