Choosing to use a competing product as an end consumer would require an immense sacrifice (like refusing to board your flight if it happened to be a Boeing, which you might get a rebate for?). Only if a significant amount of end consumers protested would the actual plane consumers (the airlines themselves) take notice - or if public opinion shifted to the point where there was a significant externality attached to purchasing a Boeing plane, but that certainly isn't the case now and I'd bet that Boeing has found some way to compensate airlines for the cost of having their planes grounded.
For example, if airline A flies MAX and has a ticket for 200 and another airline B has the same route for 400 on A320, most people I know would still fly the MAX because they cant afford to be picky.
I think talking with your wallet works only when the price is relatively inelastic
The Max has issues, for sure, and I will be weary of that as well as the upcoming 777X, but I wouldn't hesitate to get on any prior 737 or other Boeing model.
How many vacation days would you sacrifice out of your week in Cancun to stand by that belief?