People whinge about modern tech being too complicated but have never really taken the time to experience and understand it - they just assume it is and come up with utter garbage muttering "marketing" etc. But it isn't any more complicated at all and often actually easier to maintain.
For example: Di2 and eTap are easier to adjust than mechanical because they allow for electronic micro-adjusting. I can simply hold a button on my eTap brake levers and micro-adjust if necessary whilst riding.
Changing brake pads for a disc braked bike is no more difficult than for a rim braked bike.
Swopping cassettes, chains etc are easy too. Chains now have 'powerlinks' etc which make installation even easier than before.
Tubeless? Easy. Trick? After installing the rim tape properly, not allowing any gaps, put the tyre on the rim and run a tyre lever halfway on one side to partially seat it onto the edge of the rim. Repeat on the opposite side. Do this and you can inflate the tyre without the need of a compressor./ Airsoft etc and leaks from not putting in sufficient air to seat the tyre properly is avoided. I've got 5 pairs of tubeless wheels, all done myself, all no hassle at all.
I use Park Tools including their repair stand and can highly recommend them (plus their videos as mentioned by another Poster above if you need help) but there are many alternatives. With the correct tools, all bicycle-related work is not difficult at all. Keep a bike in good order and none of the problems an incorrectly maintained bike will throw up such as seized components etc will be an issue.
Can you please go into a little more detail on how you get the tubeless tyres on ....I'm always keen to try hacks to make this easier as I am doing just that now
Last tip I read was to start opposite the valve ...get the tyre rims in the channel then get one side in before moving to the other side ( maybe a different thread to this one ,,sorry )