Under what circumstances is it worthwhile to pursue a 0-1 product that can be easily duplicated by a large competitor?
The two biggest things to ask are: "would they?" and "could they?". This is both a question of strategy and tactics - of both you, and the competitor. My first startup was a directly competitive product with multiple established players in the space, so this was a topic from day one. My second startup is a "first of its kind" product with no direct competitors initially, but we have asked ourselves this same question a few times about large, tangential incumbents as we've built our company.
The best way to do this exercise is via SWOT analysis: for you and your competitors. Map out:
where you are uniquely positioned to play and win (via your opportunities and strengths)
where your competitor is uniquely positioned to respond (via their opportunities and strengths)
where you are vulnerable to competitive threats (via your weaknesses and threats)
where your competitor is vulnerable to you (via their weaknesses and threats)
Usually, large competitors don't have the agility to duplicate what you're building at anywhere near the speed that you're able to move as a startup: don't underestimate the time it takes large companies to make decisions, alter strategy, and execute on that strategy. They usually work in annual cycles for large strategic initiatives, and quarterly cycles for execution. Most large companies don't have the process in place to pivot outside of those timeframes without it being incredibly disruptive: take advantage of that.
That being said, it is also important to consider how aggressively you are going to market and where you decide to play - it's not wise to go poke a bear (a large competitor) directly, but smarter to build up a strategy that will sneak you in through a side or back door into the market.
This also brings up the importance of how you get to PMF and how quickly you are able to get to PMF. If you do it slowly, and very publicly, it will give competition the time to say "hey, maybe we should do something about that". Think carefully about how you market yourself when you are very early: do you private beta, get MVP validation, then go to market more broadly? Or do you "launch" more publicly earlier? These strategies will depend on the competitive landscape and what you strategy is on entering the market.
There is a fantastic book on this topic called Playing to Win: How Strategy Really Works that I highly recommend.
Here are some considerations for continuing to pursue a 0-1 product even when you have a potential large competitor:
A niche focus that you feel is a significant differentiation that you can capitalize on. Even better if this community is easily engaged with you or you are easily able to tap into it
Early mover advantage: if you believe, being early in this market helps you penetrate the market better and users will remember the brand even when there is a recognized large player moving in
Unique idea: something that you feel is hard to replicate, even for a large competitor. It might be UX, a specific feature which you are able to patent etc.
A strong partnership with a large entity that is willing to distribute your product to the market. This ensures you have the user acquisition aspect sorted out early on
You are able to patent the technology so that it cannot be duplicated easily
You can iterate and move fast on the product as compared to a large organization which will move slowly
If you believe that your startup/product would be acquired by this large competitor anyway. (acquisition target)
These are some considerations but this is not an easy decision to make without understanding the product, users, feature set and core differentiation.
I think the main key advantage here for a smaller startup vs establish business is when speed and execution are on your side because youll surely outpace larger businesses in almost any product you want to build. If you can deliver value faster, iterate more efficiently, and create an experience that deeply resonates with your niche audience, you can carve out a market position before the bigger player even gets moving.
Now why is that the case?
Because big businesses operate in bigger silos and at a larger scale in terms of strategy. It can easily take a company 6 months to formulate a strategy and another 6 months to put it in motion. Thats how it is at that level of growth because many decision makers, policies around data, etc will all be a thing to consider.
One way or another youre going against a big guy here. The smart way is to choose a good GTM for your product that doesnt set alerts to that guy. This is where niche focused outreach, beta users, closed tests, private demos, etc can be a good thing here but youll lose some market share as a result because youre not letting your product run viral or have a growth loop by many users. So keep that in mind.