I think most United fans are not really clear on what's involved with rebuilding a squad and changing the tactics. They want success without the effort (which in this case is just suffering through watching some bad results) and panic when it doesn't happen, spending hours every day winding each other up on the internet about how the club isn't doing enough minute-to-minute to fix the situation. The thing is, firing the manager doesn't really move the club forward, it's just restarting the process and giving you a false sense of optimism and novelty while the exact same pattern starts over again, only now you've convinced yourself the previous manager is incompetent, and that we have to do the exact opposite of everything he wanted to do, necessitating yet another squad rebuild.
It is early to be writing off the club's transfer dealings since EtH got here, let alone nailing the coffin shut on the footballing project as a whole. We've got a couple of good recent examples of high-level English clubs that rebuilt their squads, changed the tactics (without the infinite money tap) and challenged for the title again: Liverpool and Arsenal, and it took both of them about two and a half seasons before they even began their legitimate title-challenging seasons.
Klopp started at Liverpool on October 8th, 2015, got 7 months get a look at the squad and train them, and finished 8th. They then finished 4th in 2016-17, 4th in 2017-18, and 2nd in 2018-19.
Arteta started at Arsenal on December 20th, 2019, got 5 months to get a look at the squad and train them, and finished 8th. They then finished 8th in 2020-21, 5th in 2021-22 and 2nd in 2022-23.
It's important to understand how useful it is to lower the expectations and suffer through a few seasons of mediocre results if necessary to implement a new style of play and drop some of the dead weight. It's not because it's easier on the players or manager, but because re-training the players to play in a different way takes several months and will result in dropped points. It's even harder when you're starting with a squad that only has 1 or 2 players who even have the skills to implement the new play style, let alone the knowledge and training. Lowered season expectations also allows the club to shop around for bargains or even leave a gap in the squad open between two windows if a good value transfer doesn't materialize.
Ten Hag was forced to mostly abandon his style change last season after two matches and play in a modified version of the tactics the players were comfortable with. He's clearly trying to go with new tactics this season, playing fairly directly to get the ball high up the pitch and counter-pressing when the team loses possession. Unfortunately some of the players don't seem comfortable with it yet or are lacking the attributes to implement it (Rashford, Bruno, maybe Shaw, maybe Casemiro).
That he wants to bring in players he's managed or is familiar with is understandable and a smart thing to do. Klopp did it and so did Arteta. If you want to change the style of play quickly, you absolutely need some players who know what they're supposed to be doing and have experience doing it. Brighton is a good example of a club that play very well with a number of players in the squad that aren't world class but know what they're supposed to do and are good at it.
The transfer strategy isn't the disaster people are making it out to be. A simple look at the ages of the players transferred in (at the time of transfer) so far shows they're not shortsighted attempts at improving the squad immediately at the expense of long term success. Casemiro and Eriksen are the only 2 older players and they're 30, but were clearly bought because we desperately needed midfielders to make an immediate impact, something which only the stupidest of you would deny.
Malacia 23
Martinez 24
Antony 21
Hojlund 20
Mount 24
Onana 27
They haven't all come good yet but it's still pretty early, and every big club has expensive transfer flops, with United being no exception. Guardiola and Klopp both have had expensive flops at their current clubs, Real and Barca both have paid staggering fees for players that ended up providing far less to the club than Maguire or Pogba did.
People just need to stop doomscrolling and do something else between matches for a bit. It's been over a decade since United was the kind of club from whom you could expect a comfortable title race, and well past time where we need to get used to not dominating every match. We've got a manager who looked well on his way to being one of the top managers in Europe to come in and build a top team, and he was never going to do it in 12 months.