There is a better way to track a decade of play, and it starts by rethinking the spreadsheet itself. The monthly summaries you have been posting since April 2017 are a remarkable record, but the way you are storing them now will eventually become a trap. Your current layout, with each year as a row of monthly columns and a running all-time total, works for a simple sum, but it will fight you the moment you want to ask a question like "Who played the most in the fall?" or "What did our busiest year look like?"
The core issue is that you are mixing data with presentation. Your sheet is designed to look like a report, not to be queried like a database. For a hobby that has already run for nine years and is heading toward a decade, you need a structure that treats each monthly entry as a single row of facts: the year, the month, the player name, and the hours. That is it. From there, you can use a pivot table or a simple SUMIFS formula to generate any summary you want, including the exact tables you are already posting. The all-time column becomes a calculated measure, not a manually maintained cell.
What will bite you in the future is not the math, it is the layout. If you keep adding columns for each month, you will eventually hit a wall when you want to compare trends across years or filter by player. You will also have to update every formula whenever a new player joins or someone leaves, which is exactly the kind of tedious work that kills a hobby log. A long, narrow table with four columns (date, player, hours, and maybe a notes field) is boring to look at, but it is infinitely more flexible. You can sort it, filter it, and chart it without touching a single formula.
The good news is that you have already done the hardest part: you have consistently recorded the data for years. That is rare and worth protecting. Your instinct to move this into Excel is sound, but resist the urge to mirror the monthly posts in a grid. Instead, spend an afternoon converting your existing summaries into a flat table, then build your monthly report as a pivot table. You will never have to rework the structure again, and you will free yourself to explore the story your data tells, like who crossed the 100-hour mark first or which year saw the most total play. That is the kind of insight worth having, and it will make the next decade just as easy to track as the first.