To be fair, just about ANY keyboard will last for a long time, if you take care of it.
If you can afford the flagship board from a company and you want that, then go for it. If you want to be a bit frugal, then go for the mid-range offerings. If you want to be REALLY frugal, then go for the entry-level.
The thing is that even the entry-level offerings offer a lot of bang for the buck. If you take care of it (keep it clean, keep it covered when not in use, keep the dust out, etc...) any keyboard will last a long time.
I have keyboards in my studio that are 30 years old now. Yes, I have had to maintain them, and that requires putting new memory batteries in them (something that is really not a problem now with today's keyboards), keeping them covered, and keeping them clean.
Electronics are going to wear out over time, it is the nature of what they are.
Granted, getting a higher-end keyboard may come with better parts inside, but there are MANY parts that are used across the entire product lineup and they have done it for a long time. A good example would be the joystick for Korg keyboards. If you look at the M3, M50, PA series, Krome, Kronos, new i3, and new Nautilus, they all have the same joystick. I have replaced the joystick in my PA700 twice and it is the same joystick that they use in so many other boards in their product lineup. I am not saying that is a problem, but some parts are going to be the same, no matter which product you buy. If memory serves, the Kross and Krome share the same keybeds (in the 61 and 88 key versions).
If you really wanted to grow into a keyboard, then a flagship may be the way to go, because, at least with the Korg Kronos, there is A LOT to explore and you will be busy for years on one of those.
With that said, I have the Kross synths in my studio (actually, 4 of them, among many other synths). My Kross synths are not even the Kross 2 version - they are the original Kross 1. I still get A LOT of mileage out of them. The Kross is their entry-level offering. I use one live (actually two, an 88-key and a 61-key) and they are my main piano sounds for live work. I do have another digital piano at home for solo piano work, but the Kross really has great sounds in it and the possibilities are not easily exhausted. I also have the PA700 and it is a remarkable instrument. I have owned one since they came out in 2017 and it is my main songwriting tool in the studio. It is also the main board I take when I am doing solo performances of my original material. It is also the exclusive board I take to the nursing homes to play for the residents. It is an arranger keyboard with backing styles, but also features a full synth engine and I can program whatever I want in that thing.
I have recently bought the entire Yamaha Reface lineup. I got the YC (organ) and CP (EP stuff) a couple of months ago, and just got the Reface DX (FM synth) and CS (virtual analog synth) in yesterday. They are really fun too, and are basically modules in my live rig for the band(s) I am in.
I also have a number of Ensoniq pieces in my studio, namely the VFX and VFX-SD (and some rack mount variants). When I turn them on, I still am amazed at what I can pull out of them and I have been using Ensoniq products since 1990.
If weight is a consideration, then I would stick to a 61-key unit, as they are lighter. The Kross 2 weighs around 10 pounds, I believe. The Kronos 61 is probably around 25-30 pounds, I believe. If you need an 88-key keyboard for piano stuff ( I know you say you are a beginner), then the Kross 2 is around 27 pounds. It is a lot easier to transport than the Kronos 88.
I know that you have probably already done so, but listen to videos of the different keyboards and see which one piques an interest. Then, go down to the music store and try them out and see which one really zings you. You know it is the right one when that happens. If you do not have access to any of these boards and are relying on videos and forums like this, make sure that wherever your get your keyboard from has a good return policy, in case you need to return it and try something else out.
To throw ANOTHER kink in the wheel, if you want a quick and dirty keyboard for performance, check out the i3 from Korg (the new version, not the original version from the 90's). It will have any sound you want and it sounds pretty good. It is a budget offering from Korg and comes in at around $500 USD (at least it does at Sweetwater). It's sound engine is not the most current, but it has all of the sounds you want, allows you to layer up to 4 sounds (3 Upper and 1 Lower), has built in rhythms, weighs about 10 pounds, and can run on betteries. It also features a 5-Pin MIDI Out port, so you can MIDI other keyboards to it in the future if you like. I have one of these too, and I intended to use it as a bottom keyboard in my rig and for the gigs I used it on, it worked well, especially since I was layering sounds internally and via MIDI. I use it at practice now because it is so light and I am NOT bringing my entire live rig to a practice unless it is right before a show...
Grace,
Harry