What is the opposite of "early birds"
Solution 1:
In the specific context of technology, the standard term is late adopters. Here is a definition from the Macmillan Dictionary:
someone who is slow to start using or buying a new product, technology, or idea.
The phrase has made its way to the New York Times.
Edit based on comments from @1006a: The term late adopters comes from analogy with early adopters. The latter phrase was first introduced by Everett Rogers in his theory regarding the diffusion of innovations. Rogers identified five classes of individuals: innovators, early adopters, early majority, late majority, and laggards. The last three are sometimes combined into a single category, followers.
Technically, then, follower would capture the sense you want of being part of the majority: as you said in a comment to a different answer, it would be
Someone who behave[s] like most of us.
But if you wanted to emphasize the lateness of your adoption, laggard would fit better. However, the specialized meaning of these terms is unlikely to be known to most audiences, while late adopter would be fairly straightforwardly understood. The New York Times headline would not read as transparently if "late adopters" were replaced by "followers" or "laggards", for example.
Solution 2:
The OP seems to mean the people who buy Gadget X after all the post-release bugs have been found and fixed and the price has gone down. If the OP wants to keep the avian metaphor, call them the wise owls.
Calling them wise owls is appropriate on two levels: (1) owls are mostly nocturnal, contrasting with the early birds; and (2) owls are birds of prey. The wise owls prey on the impatience of the early birds who have to discover the bugs and pay a higher price.
As for the term wise owl, Wikipedia states that:
The modern West generally associates owls with wisdom. This link goes back at least as far as Ancient Greece, where Athens, noted for art and scholarship, and Athena, Athens' patron goddess and the goddess of wisdom, had the owl as a symbol.
Solution 3:
I don't like to be a beta tester, I'm kind of a late majority type.
Marketing industry has terminology for the various types of consumers. There is no opposite to an early adopter- it is just one of five broad sweep categories.
Marketers have broken consumers down into different groups and created this snazzy curve called the Innovation Adoption Curve, [...]
Adopter Category #1: Innovators — [...]
Adopter Category #2: Early Adopters — [...]
Adopter Category #3: Early Majority — Early Majority consumers collect more information about the product and will weigh the pros and cons before they make a decision. They listen to their opinion leaders and will rely on their groups’ opinions instead of forming them for themselves. They’re an important group nonetheless and should not be ignored! Early Majority group members are positioned between the earlier and later adopters and are deliberate in their data collection process.
Adopter Category #4: Late Majority — Alright, now we’re to the skeptics. Late Majority consumers adopt a new product mainly because their friends have all adopted them and they feel the need to conform. This group is typically older and has below average income and social status. They listen to word-of-mouth communication over mass media, since they trust their friends more.
Adopter Category #5: Laggards — Laggards do not rely on group norms and values, just like Innovators. [...] - https://www.qualitylogoproducts.com/blog/innovation-adoption-curve/
Also see Wikipedia