I feel like the near future looks quite bullish, this is why we tend to look for the situation to be a bit more positive, and that is why it is normal to think about the bullish period. Plus, OP mentions "profitable" which means that it makes people think about the bullish period a lot more. I think it should be noted that we are talking about a situation that is not going to be all that simple, because usd and eth are good for very different periods. I am not saying that it is not going to end up with a bad situation, there could be moments when it is bad, or I could be totally wrong and it doesn't go well at all.
However, if you look at the market right now, and check out the few months we had so far, I would be easily saying that it has been great and will continue to do that. In that case, if the price keeps being bullish like it has been so far, then I am going to guess that it is going to be as great as it gets and you will be right to pick that pair.
Yes, considering today's market conditions and answering the OP's question it was a more logical to give an example and answer with a positive scenario, just like in my first comment. However, if we need to answer by taking all conditions into consideration, it is necessary to consider what could happen in case of a possible negative scenario which I stated in my second comment. In general, considering the OP's question and current market conditions it would be more accurate to interpret it through a positive scenario.
Moreover, as you mentioned if we have to make an evaluation according to today's market conditions it wouldn't be right to think of bad scenarios for now. Of course, it is also very important to act knowing that the market can always reverse and all the possible scenarios can happen.