The problem is when you think ahead a bit. Lets say you go into debt buying good players you can't afford long term. And you achieve your goal and you advance up to the next league level. Except, now you have to sell the players you can't afford, plus you are already in debt, so you can't buy any new players for awhile until you play enough games to get some money ... which might be half of the next season depending on how far into debt you go. On top of that, you might even be paying a salary floor tax on your remaining players as your starter set players may not make enough to pay the league min at the next level.
So, now you're up in a higher division, still playing with your starter set players without the expensive ringers you got to win the league last year. That's not going to be a pretty season. Certain relegation seems to be the most likely outcome. Be happy the league doesn't keep a record for worst point differential ever.
Which means two years from now, you are right back where you started, except you are out the money you paid in salaries to the expensive players while you had them, which bought you a brief visit to the next highest league but not much more. May also cost you some ticket revenue. I don't know whether a winless higher division team can draw more people than a lower division team that's driving towards a league title.
If you build your team slower, and advance a season later, you still might be right on the line for whether you are good enough to stick at that level. But, at least that way you didn't throw away money along the line for the expensive ringers.
If you can't tell by now, my advice is not to do it. :) Buzzerbeater seems to be a game of long term thinking and planning.