The OP is right in that we should never spend to the extent that if the Liebherr money was suddenly withdrawn the club would be in trouble. Pompey's owner Sacha Gaydamak was rich when he bought the club, he could afford the spending at the time he made it - it was only once Daddy got into trouble for arms dealing and tax evasion that the money dried up and the club began to spin into admin. Although the Liebherr's are a totally different propostion, unfortunate things can happen to anyone. Does everyone know for sure their entire fortune wasnt tied up in Snoras Bank, or in whichever is the next bank to go under?
Of course if money is available from the Liebherr's we should take it with thanks- but structured in a way that we dont need it recurrently eg if they only made capital injections for the Staplewood upgrade or to buy big players, as long as the recurrent costs like wages could be funded from the revenue generated by the club.