The most damning statistic that contributed to the scarcely believable £163.8m debt Bolton Wanderers revealed on Tuesday is the £50.7m loss they posted in the year to June 2013 alone.

This followed a fall in turnover from £58.5m to £28.5m as the effect of relegation from the Premier League the previous season was felt. As Phil Gartside, the chairman, said: "Looking forward we have to recognise we are no longer a Premier League club in the Championship but a Championship club with ambitions to play in the Premier League."

Perhaps a more encouraging note for supporters and anyone who wants clubs run on a robust footing would have been sounded if Gartside had made clear that the mistakes in overspending will be learned from and not repeated. Gartside and Eddie Davies, the owner who is owed nearly all of the £163.8m, must shoulder the responsibility for the position the club find itself in.

The wage bill now stands at £32.7m, its lowest level since 2007 when Bolton were still firmly a Premier League club, so the question must be asked why, over the following five years, this and other overheads continued to rise despite the greater monies received from operating in the world's richest league.

Bolton last made a profit in 2006. Since then year-on-year losses have risen steadily to the current amount. This means that the £50.7m black hole suffered in 2012-13 has been seven years in the making – time enough, surely, for Gartside and Davies to have warning to arrest this. In 2007 a £2m loss was returned, the following year it was £8m and by 2010 it had jumped to an alarming £35m – this last figure all but tripling the previous year's £13m.

In the haemorrhaging of £50.7m over 12 months Wanderers become a member of the club no one wants to join by being the fifth to lose £50m-plus in a year.

Manchester City, who have done it four times, Chelsea (seven), Liverpool and Aston Villa (once each) are all entities with far greater finances and revenue streams than Bolton who, even before relegation two seasons ago from the Premier League, struggled with attendances that could be lower than several Championship clubs and even one in League One.

To place the £163.8m owed in further perspective, only Chelsea, Manchester United and Fulham have more debt from the most recent available figures. As Gartside confirmed, the fact that Bolton can shoulder such crippling losses to remain a going concern is solely down to the benevolence of Davies.

Gartside said: "This year's results show the difficulties faced in the football business when a club has enjoyed a sustained and successful period in the Premier League, in our case 11 years, then suffers relegation back to the Football League Championship. The ever-widening gap between the two leagues makes the transition extremely difficult, even with the benefits of parachute payments from the Premier League."

Regarding Davies, who paid £2.25m in 2003 to increase his shareholding from 29.7% to 94.5% to take over Bolton, Gartside offered thanks that the club remains solvent while stating that due to financial fair play rules in the Championship, alternative incomes have to be found. "It should go without saying that Eddie Davies continues to provide a humbling level of support to the club," Gartside said.

"However, the financial support given by owners is no longer possible in this league without severe penalty. We are responding to a changing environment by improvement and development of the wider Burnden Leisure business interests. This year we secured sole ownership of the hotel [at the Reebok Stadium], expanded our education business and applied for planning permission to increase our non-football operations to improve revenues over the medium to long term.

"We will continue to invest, both in the long and short term, where the returns can be justified. However, financial fair play rules require an alternative funding structure and Bolton Wanderers is very much moving towards a self-sustainable future."

The numbers that illustrate how Bolton find themselves so dependent on Davies to avoid entering administration ahead of potential extinction are alarming. Despite season ticket prices being frozen last season, attendances at the Reebok Stadium fell 24%, while sponsorship dropped from what was a relatively minuscule £4.3m to an almost insignificant £1.4m, a 68% decrease.

All of this occurred despite the club reducing staff and general administration costs. In a statement Bolton said: "Total staff costs for the year were £37.4m, down from £55.3m, as a result of a number of players leaving the club as well as the evoking of relegation clauses in a number of players' contracts and making significant changes in overheads. General administration costs reduced by 10% to £14.1m from £15.7m."

Davies, sources at the club claim, has no plans to walk away in the near future meaning the owner's ongoing commitment should be secured. There is also an insistence that a five-year plan is in place to address the debt. Yet Davies could hardly pull out of the club when £151.3m of debt is owed to him via his Moonlight Investments Ltd vehicle.

What seems clear is that the £163.8m owed by Bolton places the future of a founding member of the Football League in real jeopardy and this amount should surely not increase further.