When you say "scientists believe" it is about the consensus of the current academic community. That does not mean the consensus is correct. A few years ago academic consensus in cosmology was that the expansion of the Universe was slowing, that consensus is now believed wrong.
In social sciences, where there are many more confounds than just Dark Energy and Dark Matter, consensus can shift even quicker.
Anticapitalist Mastodon instance. Party means fun, not political party. But we're still political.