Almost every year there are reasons to be bearish. Usually pretty good reasons. Probably ones that could persuade me.
I pretty much have to put that aside and acknowledge that an investor should have a bullish bias. US companies want to make money and I think they will likely make money over time.
Are public US companies going to be worth more or less in 5-years, 10-years, 20-years? Well, then, is the S&P 500 index going to be up or down in 5-years, 10-years, 20-years?
It's fine to be cautious. It's fine to be bearish. It's just that being bearish is swimming against the tide over longer timeframes IMHO. So, the average bull will do better than the average bear. If you want to be a bear, you have to overcome that.
At least that's how I see it.