Lemmy has a lot of obstacles that will prevent it from truly going mainstream:
The community browser is complete dog shit for discovering content on different instances, and trying to view another instance's content from your own community is just needlessly complex. Discoverability is still a lot better than Mastodon though, where you'd look at all post and see nothing but hentai reposting bots regurgitating stuff that isn't even allowed on NSFWLemmy...
Due to the nature of federation, you also run the risk of committing to an instance only for them to defederate entirely, or disassociate from content you want to see but they don't agree with. Beehaw is a very good example of this.
As there's no option (yet) to migrate to a different instance, and Lemmy is a FOSS project that cannot be monetized in the same way as a traditional social media site, what happens when instances start shutting down due to being unable to keep up with server hosting costs?
I cannot speak for the iOS option available, but Jerboa is barebones. For example, you can't even tap on a post/comment reply in your inbox to go to that comment's permalink and view the context. This is incredibly basic functionality for any social news aggregator. Even with the fediverse in general surpassing 150,000 users, I don't see Lemmy getting the same level of third-party app support as Reddit had.
These are all valid complaints, but I feel like you need to put this into perspective. This platform has blown up in the last week, change is going to come but it’s going to take some time. I’m sure it will go faster now that it is really taking off though.
Some are transitory however - 1, 3 and 4 all reflect the current state of Lemmy and the similar Kbin are in currently. The Reddit issues were unexpected and people have migrated en masse to Lemmy/Kbin and have found was is in many ways Alpha software. This issues will mostly be resolved with time, and that is probably accelerated now as more people means more people interested in development, and motivated by anger at Reddit. I don't think Lemmy/Kbin will replace Reddit right now, but I think a new trajectory has been set. Communities are hitting critical mass to keep growing.
Look at Mastodon, it's at 1.2m-2m active users each month; it is still small fry and niche compared to Twitter but it exploded thanks to Twitter's mess, and is growing. I think we're seeing something similar with Lemmy and Kbin, but this is just the start of a long road and an expanded community will accelerate improvement and growth.
But point 2 is fundamental to the fediverse - fragmentation due to defederating could be a concern. I get Beehaw's motivation but I think their actions will consign them to a niche part of the Fediverse, but that may be what they want. Ultimately I suspect the biggest servers will dominate a main interconnected fediverse through sheer size and notoriety - new servers will need to federate to the big players to grow. It's not necessairly a bad thing - but people may end up signed up to a "main" large interconnected "fediverse" and separately to smaller niche communities they're interested in but sitting in their own walled gardens/bubbles. It's not necessairly a bad thing though - it is just different to what people are used to with social media like Reddit. It'll be a trade off - servers and communities have complete independence and some will go for what suits them - part of a big fediverse or only federating to smaller aligned communities.
A lot of these issues are temporary. Also, this is all happening very fast, it's entirely possible that some other website/service will pop up that'll be a lot better thought out.
Reddit was already well established and functional during the Exodus of Digg, so there wasn't much discussion about where to go. Today we have no solid alternative, so people are trying Lemmy, Kbin, Mastodon, Squabbles and other websites.
Server costs are not as high as Reddit made us believe. You can probably run a 10 user instance for less than 10€/month.
If the instance is good donations could keep it up forever, not even expensive donations. Certainly a fraction of what reddit is asking for reddit premium.
It's requirements will grow, but it's still mostly text and some images. Mastodon is kind of big (not twitter big but bigger and more active than lemmy) and there are people still self hosting their instance and there's lots of donation supported instances.
I think fediverse being instance-oriented should scalate well. As no instance really needs to hold the whole thing by its own.
I studied something completely unrelated with computer science. I started with programming and then with general computer science and now I know a lot of things and I'm quite probably going to land a job in IT field next year. It's never late to learn something new.
Coding is hard though, especially when you go past the basic tutorial stuff (Hello World, if statements, for/while loops, libraries, etc.) Actual computer science and understanding all the technical and mathematical aspects of computing is orders of magnitude harder than writing some C# or Javascript code.
Last time I actually tried to make an effort to learn how to code was back in the days when /r/CarlHProgramming was still active, long before Carl Herold was arrested on heinous child sex crimes.